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Author Archives: billscully

  1. LC Crimp & Cleave Termination Instructions

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    for 50 and 62.5 µm GiHCS®, 200 µm HCS® LC Connectors

    Important Safety and Warranty Information

    Please Read First!
    Please make sure to READ and understand the termination instructions completely. Improper assembly will cause poor termination results and cause damage to termination kit components.

    Download the pdf document for the full instructions

    Make sure you WEAR eye protection during the termination process. Bare optical fiber is sharp and may splinter; handle very carefully and make use of the provided fiber optic shard disposal container.

    For more information please CONTACT the sales representative in your region or call the factory for technical support:
    Mon-Friday, 8:00 am-5:00 pm EST.
    860-678-6636
    770-798-5555 [Outside the USA and Canada]

    Content
    LC Termination Kit Contents
    Related Products and Accessories (Sold Separately)
    LC and LC Duplex Connectors
    Insertion Loss Test Kit

    Termination Instructions
    Step 1: Slide Strain Relief Boot
    Step 2: Remove Outer Cable Jacket
    Step 3: Remove ETFE Buffer
    Step 4: Install Connector Body
    Step 5: Cleave Optical Fiber
    Step 6: Install Anti-snag Latch or Duplexing Clip

    Maintenance & Trouble Shooting Guide
    Importance of Cleave Tool Cleaning
    Cleave Tool Cleaning Kit
    Troubleshooting


    LC Termination Kit Contents

    Kit Contents
    Part Numbers/Description
    DT03732-LC1 . . . . . . . . . . . GiHCS LC Termination Kit
    DT03732-LC2 . . . . . . . . . . GiHCS LC Cleave Tool Only
    P76859 . . . . . . . . . . . . . . GiHCS LC Instruction Manual
    AP01224 . . . . . . . . . . . . . . . . . . . . . . . Cable Strip Tool
    BT03865-07 . . . . . . . . . Crimp Tool LC (Black Handles)
    CP01229-22 . . . . . . . . . ETFE Buffer Stripper w/ prong tool and brush
    AP01225 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scissors
    K60791 . . . . . . . . . . . Optical Fiber Shard Disposal Unit
    K60792 . . . . . . . . . . . . . Alcohol Prep Pad (Box of 100)
    Other Items Required (not included in kit): Safety Glasses, Marker
    Order an OFS LC Termination Kit Number DT03732-LC1 Now


    LC and LC Duplex Connectors

    Related Products and Accessories (Sold Separately)
    Part Numbers/Description
    P26763-01 . . . . . . . . LC Simplex Connector (Beige Boot)
    P26763-02 . . . . . . . . . LC Simplex Connector (Black Boot)
    P26764-01 . . . . . . . LC Duplex Connector (2 Beige Boots)
    P26764-02 . . . . . . . LC Duplex Connector (2 Black Boots)
    P26764-03 . . . . . . . . . . . . LC Duplex Connector (1 Beige + 1 Black Boots)
    P10188-15 . . . . . . . . . . . . . . . . . . Insertion Loss Test Kit for 50 and 62.5 µm GiHCS LC Connectors
    P16247 . . . . . . . . . . . . . . . . . . . . Cleave Tool Cleaning Kit (Includes cleaning fluid and safe cleaning swabs)


    STEP 1:  Install Strain Relief Boot

    Slide STRAIN RELIEF BOOT (tapered end first) onto cable end and slide approximately 3 inches [76 mm] out of way.


    STEP 2: Remove Outer Cable Jacket

    • Mark cable outer jacket 2.5 inches [63.5 mm] from cable end with a marker
    • Using 2nd hole (marked 1.6) from the open side of the cable jacket strip tool, remove the 2.5 inches [63.5 mm] of outer jacket.

    STEP 3: Remove ETFE Buffer

    • Insert the buffered fiber through the guide tube of the ETFE Buffer Strip Tool, all the way in until the cable jacket bottoms out inside it.
    • Holding cable securely, squeeze the tool’s handles to cut ETFE buffer then PULL STRAIGHT to remove the ETFE buffer.

    • With alcohol prep pad folded in two, wipe the surface of fiber where the ETFE buffer was just removed.

     

     

     

    STEP 4: Install Connector Body

    • Locate the CONNECTOR BODY subassembly into the CRIMP TOOL nest as shown. Close the crimp tool handles lightly to secure connector in nest, but do not yet apply crimp
    • Insert stripped fiber into CONNECTOR BODY subassembly until the cable jacket bottoms out inside the connector
    • Squeeze handles of CRIMP TOOL to apply crimp. CRIMP TOOL will not release until fully crimped.
    • Remove CONNECTOR from CRIMP TOOL nest. Slide up and
    • install BOOT onto CONNECTOR.

    • Locate the CONNECTOR BODY subassembly into the CRIMP TOOL nest as shown. Close the crimp tool handles lightly to secure connector in nest, but do not yet apply crimp
    • Insert stripped fiber into CONNECTOR BODY subassembly until the cable jacket bottoms out inside the connector
    • Squeeze handles of CRIMP TOOL to apply crimp. CRIMP TOOL will not release until fully crimped.
    • Remove CONNECTOR from CRIMP TOOL nest. Slide up and
    • install BOOT onto CONNECTOR.

    STEP 5: Cleave Optical Fiber

    • Holding the CLEAVE TOOL in a horizontal position, grip the handle while leaving your index finger free to actuate trigger
    • Gently insert CONNECTOR BODY into cleave tool as shown. Be sure to have it fully inserted and release the CONNECTOR BODY
    • Using index finger, slowly depress trigger to perform the cleave operation. The cleave process is complete when the optical fiber snaps away
    • from the connector. Do not release the trigger just yet!
    • Before releasing the trigger, remove CONNECTOR BODY from the
    • cleave tool and grasp the optical fiber scrap while releasing the trigger.
    • Gently remove the scrap fiber from the cleave tool while keeping it away from the tool’s diamond blade. Place the scrap optical fiber into the fiber optic shard container for safe disposal.

    STEP 6: Install Anti-snag Latch or Duplexing Clip

    Simplex Connector:
    • Spread the clip slightly as shown.
    • Install the clip around the connector, aligning as shown.
    • Wrap around and snap on to secure.


    Duplex Connector:
    • Spread the clip slightly as shown.
    • Install the clip around the connectors, aligning as shown.
    • Wrap around and snap on to secure.


    The PDF document also includes a Cleave Tool Cleaning Guide:
    For cleaning your cleave tool, please order the OFS Cleave
    Tool Cleaning Kit (part #P16247) which includes recommended cleaning fluid, swabs, and complete instructions.

    The PDF document also includes a fiber optic troubleshooting guide for:

    • Dim-light termination and no light termination
    • Poor cleave quality or high insertion loss
    • If the fiber does not cleave
    • If the fiber protrudes or recesses after cleave


    Download our LC Connector Family Spec Sheet

    Visit our Knowledgebase and filter by Installation Resource to find a list of all our fiber optic instructions.

    Learn more about our fiber optic building solutions

  2. A Focus on the Critical Optical Parameter Attenuation

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    Our first article in this series highlighted some bandwidth demand drivers and introductory standards information. This article will focus on critical optical parameters starting with optical attenuation. Additional articles in this series focus on other optical parameters, including chromatic and polarization mode dispersion, splice loss, and an introduction to non-linear effects.

    Fiber Wavelength Bands

    > Download the Full Article

    There are three main loss mechanisms in fibers, and we’ll briefly discuss each. Those Attenuation mechanisms are:

    • Scattering
    • Absorption
    • Bending

    Scattering

    The first mechanism is “Rayleigh scattering” of light in fiber. This mechanism contributes most to the baseline attenuation of fiber. A certain amount of light is scattered in the glass. In the simplest of terms, scattered light is simply light that is no longer guided through the optical fiber, but instead propagates in some other random direction (an interesting side note is that OTDRs measure loss by using the light that is scattered backwards in a fiber so the device only needs to be connected to one end of the optical fiber). Since some light doesn’t transmit forward through the glass, loss occurs. The classic attenuation curve has a relationship of attenuation proportional to 1/λ4 and is driven by the properties of Rayleigh scattering. Rayleigh scattering is the result of small fluctuations of glass density in an optical fiber and is the same mechanism responsible for the blue color of the sky, when sunlight scatters off molecules in the atmosphere.

    The scattering-related attenuation properties of the glass are determined by the materials used in the glass, and are frozen in during fiber manufacturing.

    Absorption Attenuation

    Impurities may absorb or reflect light. This is why fiber manufacturers pay such close attention to the quality of materials used in the glass and to cleanliness during manufacturing. Particles as small as a fraction of a micron can be large enough to absorb enough light to increase loss.

    Besides particles, impurities in the raw materials used in the fiber manufacturing process itself can increase loss. That’s because the hydroxyl (OH) ion is a by-product of the manufacturing process. It absorbs light in the wavelength range around 1383 nm.

    The graph to the right shows the loss performance across the wavelength range with three different grades of fiber.

    > Download the Full Article

    Bending

    Bending is a very important mechanism. The cabling process and installation in the field can affect attenuation caused by bending.

    Let’s go back to Fiber 101. Fibers use the concept of total internal reflection to guide light. The refractive index profile of the core and the cladding determine how light is guided, and the term “critical angle” is used to describe when reflection turns to refraction and light is lost from the fiber. In short, when fiber is bent tightly, light can be lost.

    There are two main modes of bending – macrobending and microbending.

    While the end result of both types of bending is attenuation, the mechanisms and how they manifest differ.

    > For more details, Download the Full Article

    Other Ways Microbends and Macrobends Show Up in the Network

    The concepts of micro and macro bends affect the network in ways that are not always obvious.

    Bend-related loss is also sometimes experienced in cold temperature environments. For this reason, fiber and cable qualifications should always include tests to see how products perform in cold temperatures. As a network designer, it’s always a good idea to account for at least some optical margin for small potential attenuation increases in cold temperatures.

    Help is On the Way

    The good news is that fiber manufacturers have developed fibers that can withstand different amounts of bending while also reducing loss compared with traditional fibers meeting the ITU G.652.D Recommendation. These fibers are called bend insensitive or bend optimized fibers, and are defined by ITU Recommendation G.657.

    For the network designer and installer, a thorough understanding of various attenuation mechanisms can assist with the network planning and installation processes, enabling proper loss budgeting and the use of appropriate products for the application.

    In most situations, attenuation is the most important network parameter, and this article has provided enough background for you to be well on your way to fiber geekdom on this topic. However, fiber geekdom is a journey, not a destination, and there’s always more to learn. OFS has multiple decades of experience with fiber optic networks. Please contact your local OFS representative if you would like additional information regarding any of the items in this article.

    > Download the Article for full details.

    About the Author:

    Mark Boxer - Technical Manager, Solutions and Applications Engineering for OFS

    Mark Boxer is Technical Manager, Solutions and Applications Engineering for OFS. In this role, he assists customers deploying fiber in a wide variety of network design scenarios around the world and analyzes trends in telecommunications markets that drive new product innovation. Mark has a BME degree from Georgia Tech, and has spent his 30+ year career in the fiber industry. His experience includes varied roles in manufacturing and applications engineering for fiber-based products and markets. Other activities include inventor of six US Patents, member and past Secretary of the IEEE Power Engineering Society Fiber Optic Working Group, contributing member to the Fiber Broadband Association (FBA) (formerly FTTH Council) Technology Committee and Board of Directors member of the FBA.

  3. Placing Fiber Optic Cable in Underground Plant

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    Placing Fiber Optic Cable in Underground Plant

    1. Overview

    This document covers cable placing in conduit, innerduct, handholes, and manhole structures. The innerduct may be direct buried or placed in larger diameter conduits. In some applications, the innerduct may be lashed to an aerial strand.

    This document covers conventional cable placing techniques that are used to pull or blow (cable jetting) the cable into the conduit or innerduct.

    > Download full Article for more details

    2. General Rules

    2.1 Route Survey and Inspection

    It is recommended that an outside plant engineer conduct a route survey and inspection prior to cable installation. Manholes and ducts should be inspected to determine the optimum splice locations and duct assignments. A detailed installation plan, including cable pulling or blowing locations, intermediate assist points, and cable feed locations should be developed based on the route survey.

    2.2 Maximum Rated Cable Load

    The maximum rated cable load (MRCL) for most OFS outside plant fiber optic cables is 600 lb; however, the cable documentation should always be checked because lower values of MRCL may apply for some cables. When using pulling equipment to install cable, measures should be taken to ensure that the MRCL is not exceeded. This includes the use of breakaway swivels, hydraulic pressure relief valves, and electronic tension control systems.

    2.3 Minimum Bend Diameter

    Fiber Optic Diameter Bending During Installation

    The minimum bend diameters for OFS cables are defined for both dynamic and static conditions. The dynamic condition applies during installation when a cable may be exposed to the MRCL, e.g., while pulling the cable around a sheave or capstan.

     

    2.4 Temperature Limits

    Storage and installation of OFS fiber optic cable is limited to the temperature ranges. Be aware that solar heating due to sunlight exposure can increase the cable temperature well above the ambient temperature.

    3. Underground Optical Cable Precautions

    Before starting any underground cable placing operations, all personnel must be thoroughly familiar with local company safety practices. Practices covering the following procedures should be given special emphasis:

    > Download full Article for more details

    4. Innerduct

    Fiber optic cable is most often placed in a small-diameter innerduct rather than a large-diameter conduit. For existing conduit structures, multiple innerducts can be placed in a single conduit to provide multiple cable paths in the duct. Innerduct is also recommended because it provides a clean continuous path for the installation of the fiber optic cable.

    4.1 Diameter Ratio and Area Ratio

    Diameter and Innerduct area ratios.

    Diameter ratio and/or area ratio are used to determine the optimal cable OD that should be installed in an innerduct. Either ratio can be used, but consistently using one or the other is important to avoid confusion.

    4.2 Direct Buried Applications

    Studies have shown that vertical undulations in direct buried innerduct can greatly increase the required cable installation forces.

    5. Cable Lubricant

    Cable lubricant should be used when placing fiber optic cables. Recommended cable lubricants include Polywater4, Hydralube5, and similar cable lubricants that are compatible with polyethylene cable jackets. Both the winch line (or pulling rope) and the cable should be lubricated.

    > Download full Article for more details

    6. Cable Placing Methods

    6.1 Backfeed Technique

    The backfeed technique is a common installation method that is used to divide the cable installation into two separate pulls. The backfeed technique may also be used near equipment offices when one end of the cable must be pulled by hand into the building, or at manhole locations where the cable route changes direction.

    6.2 Forward-Feed Technique

    In the forward-feed technique, the leading end of the cable and excess cable length are pulled out of the innerduct at an intermediate manhole and stored on the ground in a figure-eight. This technique can be used multiple times during a cable installation to greatly increase the distance between cable splices.

    6.3 Figure-Eight Installation Techniques

    If figure-eight techniques are used during cable installation, the cable should be handled manually and stored on the ground. Place the cable on tarps to prevent damage from gravel, rocks, or other abrasive surfaces.

    Fiber Optic Cable Underground Installation

    When figure-eighting heavy cables (264 fibers or more), the cable stack should be offset to prevent sheath dents and cable damage. Although sheath dents do not typically damage fibers, this type of cosmetic damage is undesirable. When utilizing the offset method, each crossover point of the cable stack should be offset about 2 inches instead of being stacked directly on top of each other.

    Standard vs Offset Figure Eight

    6.4 Handholes

    Handholes are frequently used to provide access to cable splices and slack storage coils. On long cable pulls, handholes may be used to facilitate intermediate-assist placing operations. The intermediate-assist handholes are typically installed near obstacles or at a predetermined spacing that coincides with the maximum expected cable installation length.

    7. Pulling Fiber Optic Cable

    The following instructions assume general familiarity with outside plant cable placing procedures. They also assume that the innerduct is in place and a lubricated pulling tape or rope has been installed in the innerduct.

    7.1 Feed Manhole

    Breakaway Swivel Connector

    Mount the cable reel on the reel carrier so that the cable feeds off the top of the reel. Position the cable reel adjacent to the manhole and in-line with the innerduct. The cable reel should be positioned close enough to the manhole so that excessive cable length is not dragging on the ground, but far enough away to maintain slack cable in the event of a sudden start or stop during the pulling operation. A distance of 10 – 15 feet is generally sufficient. Attach the pull line to the fiber optic cable using a cable grip and swivel connector. Caution: A breakaway swivel connector is required if a tension limited winch is not used to pull the cable.

    7.2 Intermediate Manholes

    The innerduct in intermediate manholes may be continuous through the manhole or it may be interrupted. In either case, the innerduct should be positioned in a straight path from entry duct to exit duct. If the innerduct is continuous and has been racked, remove the innerduct ties and straighten the innerduct through the manhole. If necessary, slack innerduct can be cut out using an innerduct cutter. Secure the innerduct in the manhole to prevent it from creeping into the main duct during cable placing operations.

    > Download full Article for more details

    7.3 Pull Manhole

    OFS recommends the use of tension-limited winches for pulling fiber optic cable. The tension control may be accomplished by electrical, mechanical, or hydraulic methods. In any case, the tension-limiting device must be routinely calibrated as recommended by the equipment manufacturer. Cable winches that display cable tension but do not have automatic cutoff are not sufficient to protect the cable. If a tension-limited winch is not used, a breakaway swivel must be used to connect the fiber optic cable to the pulling line.

    7.4 Capstan Winches

    7.4.1 General

    Breakaway swivels do not protect the fiber-optic cable after the cable pulling-eye passes the intermediate capstan winch; therefore, intermediate-assist capstan winches must be tension-limited. The capstan must also meet the minimum cable bend-diameters.

    7.4.2 Set-up

    The capstan winches should be positioned along the cable route where the expected pulling tension will be 600 pounds or less. Proper positioning of the capstans prior to the start of the pull will eliminate construction delays caused when an unplanned intermediate capstan assist must be added to the placing operation.

    7.4.3 Slack Cable Loop

    During the pulling operation, a slack loop of cable must be maintained on the pull-off side of the capstan as shown in Figure.

    Intermediate Manhole Set-up

    7.4.4 Adding Intermediate Capstans

     If an intermediate capstan is added during the cable pull and the cable pulling eye has already passed through the manhole, a loop of slack cable must be pulled to the intermediate manhole before cable is wrapped on the capstan.

    Adding an Intermediate Assist Capstan

    7.4.5 Removing Cable from Intermediate Capstan Assist Winch

    At the conclusion of the pull, the cable on the capstan is twist free. However, one twist per wrap will be generated in the cable if it is removed from the capstan and straightened.

    8. Blown Optical Cable Installation

    Cable blowing systems use high-pressure, high-velocity airflow combined with a pushing force to install the cable. A hydraulic or pneumatic powered drive wheel or drive belt is used to push the cable into the innerduct at the feed manhole. Controls and gauges on the cable blowing system allow the operator to monitor and adjust the air flow and push force that is exerted on the cable. Some cable jetting systems use a plug at the cable end to capture the compressed air and generate a small pulling force on the end of the cable.

    9. Optical Cable Coiling

    9.1 Coils Stored at Intermediate Holes

    Many end users require that coils of slack cable be stored in intermediate manholes along the cable route. These slack storage coils are used for future branch splices or route rearrangements. It is important that the coiling method accommodates the proper coil diameter and does not introduce kinking or excessive twist into the cable.

    9.2 Fold-Over Method

    The Fold-Over Method is recommended for storing moderate lengths of slack cable. Form a cable bight and then twist the bight to form the first cable coil. Fold the coil over to form the second cable coil.

    > Download full Article for more details

    9.3 Teardrop Method

    The teardrop coiling method is recommended for storing longer lengths of cable since it is easier to roll the cable than perform repetitive folding operations. The cable is stored twist free by rolling the cable bight in a manner similar to that used on the cable end.

    9.4 Garden Hose Method

    The garden hose method is recommended for large diameter cables because only one turn of cable is handled at a time. The storage coil can be formed directly on the manhole racking as each additional loop is added. Each loop can be taped in place as it is added to the storage coil. This method can be used to store any length of slack cable.

    9.5 Coils Stored at Splice Locations

    Slack cable must be stored at splice locations to allow for splicing. Typically, a cable length of 50 to 100 feet is required for splicing purposes; however, the actual cable length may vary depending on the accessibility of the manhole.

    10. Racking Fiber Optic Cable and Innerduct

    Cable racking normally begins in intermediate manholes and proceeds manhole by manhole toward each end of the cable. Slack for racking the fiber optic cable may come from either the feed or the pull manhole depending on which end is closer and the amount of excess cable that is available. The preferred method of obtaining racking slack is pulling by hand. If the cable cannot be moved by hand, a split cable grip can be attached to the cable and the cable can be pulled using a cable winch or a chain hoist. Do not exceed the maximum tension rating or violate the minimum bending diameter of the cable while pulling the slack.

    Cable coils should be racked in a location where they will not be damaged, preferably on the manhole wall behind in-place cables. Do not decrease the diameter of the cable coils. If slack cable must be removed from the coil for racking purposes, remove one or more loops from the coil and then enlarge the coil to absorb excess slack. Tie the coil securely in place with plastic ties.

    > Download full Article for more details

  4. 5 Things You Should Know About IEEE Std 802.3cm™-2020

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    What is IEEE Std 802.3cm-2020, 400 Gb/s over Multimode Fiber?

    The work of the IEEE Std P802.3cm Task Force was approved as a new standard by the IEEE-SA Standards Board on 30 January 2020, creating the latest 400 Gb/s Ethernet standard using multimode fiber. 400 Gb/s is the highest Ethernet speed, and 400 Gb/s optical modules are needed in hyperscale (Google, Microsoft, Alibaba, and others) and very large-scale enterprise datacenters. 802.3cm defines 400 Gb/s solutions over both 4-pair (400GBASE-SR4.2) and 8-pair (400GBASE-SR8) multimode links. The IEEE P802.3cm Task Force was chaired by Robert Lingle, Jr., Senior Director of Market Strategy at OFS.

    400GBASE-SR4.2 is the first multimode standard to use two wavelengths (850nm and 910nm), enabling 100 Gb/s transmission over a single fiber pair. It takes advantage of the multi-wavelength capabilities of OFS LaserWave® WideBand (OM5) fiber with 150 meter link distances, while supporting 100 meter links over LaserWave FLEX 550 (OM4) fiber and 70 meter links over LaserWave FLEX 300 (OM3) fiber. This builds on well-established 40 and 100G BiDi and SWDM technology that has been offered by switch and transceiver suppliers over the past decade. A key motivation for the 400GBASE-SR4.2 transceiver type is support of the installed base of multimode fiber cabling, designed around 100 meter reach over OM4 MMF, as well as extended reach over OM5 MMF, especially in large enterprise datacenters. 400GBASE-SR8 uses eight pairs of multimode fiber, with each pair supporting 50 Gb/s transmission. It operates over a single wavelength (850nm). OM4 and OM5 will support 100 meter links, while OM3 can support up to 70 meters. A key motivation for 400GBASE-SR8 is support of new cabling architectures in hyperscale datacenters.

    What applications will use these links?

    400 Gb/s multimode links can be used in a variety of applications. These include not only 400 Gb/s switch-to-switch (point-to-point) links, but several new applications, including 400GBASE-SR8 – 8x50GBASE-SR breakouts, or 400 Gb/s shuffles (fig. 1). The breakout application minimizes the number of ports on the Top-of-Rack (ToR) switch, providing connectivity to higher numbers of servers from a single switch. In similar fashion, the shuffle application allows a single 400 Gb/s switch port to support 100 Gb/s links to 4 different switches. 400GBASE-SR8 supports both flexibility and higher density: a 400G-SR8 OSFP/ QSFP DD transceiver can be used as 400GBASESR8, 2x200GBASE-SR4, 4x100GBASE-SR2, or 8x50GBASE-SR. 400GBASE-SR8 is already being deployed as 2x200GBASE-SR4. 5 THINGS YOU SHOULD KNOW ABOUT A Furukawa Company IEEE Std 802.3cm™-2020 For more information, visit our website at www.ofsoptics.com 1 2 Example: 400GBASE-SR8 – 8×50 Gb/s Breakout.

    Shuffle Arrangement

    Optical Fiber Cable Shuffle Arrangement Illustration

    Breakout Arrangement

    Optical Fiber Breakout Arrangement Illustration

    What does this mean for hyperscale data centers?

    Both 400GBASE-SR4.2 and 400GBASE-SR8 applications can be used for point to point 400 Gb/s links between switches. Additionally, new applications are being deployed in hyperscale data centers. As server speeds reach 50 and 100 Gb/s, racks will contain fewer servers, leading to a change in switch architecture away from ToR to Middle-of-Row (MoR) or End-of-Row (EoR) switches. Copper DAC links are reaching link distance and bandwidth limitations that will make it very difficult to support this change in architecture, leading to demand for a low cost, short reach optical solution. 400GBASE-SR8 provides support for eight 50 Gb/s server links from a single MoR or EoR switch port, significantly increasing bandwidth density on the switch faceplate.

    Learn more about OFS and hyperscale data center fiber cabling.

    400GBASE-SR4.2 Point to Point Link Distance

    What does IEEE Std 802.3cm mean for enterprise data centers?

    400GBASE-SR4.2 is the first 400 Gb/s standard that takes advantage of the 4-pair OM3/OM4/OM5 infrastructure many enterprises installed earlier, first for 40 Gb/s Ethernet and later, 100 Gb/s 100GBASESR4, and 200 Gb/s 200G-SR4. It provides a graceful evolution path for enterprise networks, using the same cable infrastructure through at least four Ethernet generations. Future advances point toward the ability to support even higher data rates as they become needed. It takes advantage of the latest multimode fiber technology, OM5 fiber, using multiple wavelengths to transmit 100 Gb/s over a pair of fibers over 150 meters, compared to 100 meters for OM4 and 70 meters over OM3.

    400GBASE-SR8 will be used in enterprise data centers as 50 Gb/s servers are deployed. Most enterprise datacenter servers operate at lower data rates, however with 10 Gb/s server links being quite common.

    What is coming next?

    IEEE has already created a study group to investigate the development of 100 Gb/s per wavelength multimode solutions, known as the “100 Gb/s Wavelength Short Reach PHYs Study Group.” This will enable support of next generation 100 Gb/s server ports, expected in 2021-2022. By providing native 100 Gb/s support, no expensive “gearboxes” will be required to combine 50 Gb/s lanes, providing a low cost, power efficient optical solution. Beyond 2021-2022 timeframe, once an 800 Gb/s Ethernet MAC is standardized, using this technology with two-wavelength operation could create an 800 Gb/s, four-pair link, while a single wavelength could support an 800 Gb/s eight-pair link.

    See all of the details behind the IEEE Std.802.3cm Standard.
    Learn more about our LaserWave Multimode Optical Fibers

  5. Single-Mode Optical Fiber Geometries

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    Understanding Optical Fiber Specifications

    This article in our technical series will focus on single-mode optical fiber geometries.

    If you subscribed to our Light Post Emails you know we previously covered bandwidth demand drivers and introductory standards as well as fiber optic dispersion.In this article we’ll work our way through a typical fiber specification, highlighting the importance of various single-mode optical fiber geometry specifications.

    Optical fiber core specifications

    >Download for Full Details

    Cladding (Glass) Diameter – 125.0 ± 0.7 µm

    Cladding diameter is the outer diameter of the glass portion of the optical fiber. For telecommunications fibers, this diameter has been 125 microns (µm) for a very long time. On the other hand, the diameter tolerance has not always been 0.7 µm.

    Core Alignment Splicer Type Specifications

    During the 1980s, optical fibers had outer diameter tolerances as high as +/- 3.0 µm. As you can imagine, matching up fiber cores ranging from 122 to 128 µm in diameter could result in extremely high loss. This situation is why fusion splicing machines required additional technology to help align the fiber cores. This extra technology increased the price of the splicing units.

    >Download for Full Details

    Mode Field Diameter (MFD)

    Mode field diameter (MFD) is another specification related to fiber geometry. In a typical G.652.D compliant single-mode optical fiber, not all of the light travels in the core; in fact, a small amount of light travels in the fiber cladding. The term MFD is a measure of the diameter of the optical power density distribution, which is the diameter in which 95% of the power resides.

    >Download for Full Details

    Clad Non-Circularity of d 0.7 %

    Clad non-circularity measures a fiber’s deviation from perfectly round, and is measured as a percentage difference versus perfect.

    Core/Clad Concentricity Error (Offset) of d 0.5 ¼m, < 0.2 ¼m typically

    Core/clad concentricity error (CCCE) measures how well the core is centered in the fiber. CCCE is measured in microns and, of course, the closer the core is placed to perfect center, the better it is.

    Although the difference between 200 and 250 µm is not tremendously large, smaller diameter fibers can enable twice the fiber count in the same size buffer tube, while also still preserving long-term reliability.

    >Download for Full Details

    Fiber Curl

    What is optical fiber curl?

    Fiber curl assesses the non-linearity of bare glass. In other words, fiber curl measures how straight the glass fiber is when no external stressors are present. If imbalanced stresses are frozen into a fiber during the draw process, curl can result. This curl can show up during the splicing of fiber optic ribbons or when fixed V-groove splicing machines are used.

    >Download for Full Details

    In closing, fiber geekdom is a journey, not a destination, and there’s always more to learn. OFS has multiple decades of experience with fiber-optic cable networks. Please contact your local OFS representative if you would like additional information regarding optical fiber geometry specifications.

  6. Fiber Optic Dispersion and other Non-Linear Effects

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    This article focuses on the parameters that affect available bandwidth in optical fibers, and the dispersion mechanisms of various fiber types and non-linear effects.  Dispersion describes the process of how an input signal broadens out as it travels down the fiber. There are several types of dispersions that we will cover. We’ll also take a cursory look at other important nonlinear effects that can reduce the amount of bandwidth that is ultimately available over an optical fiber.

    Dispersion

    Fiber Optic Dispersion Bandwidth Illustration

    Most of the traffic traveling through fiber networks takes the form of a laser pulse, where the laser is pulsed on and off, effectively forming a digital square wave comprised of “1”s and “0”s. Dispersion causes a pulse to spread out over time, effectively rounding the edges, and making it harder for the detector to determine whether a “1” or a “0” is being transmitted. When this happens, the effective bandwidth of the link is reduced. The three main types of dispersion mechanisms are modal dispersion, chromatic dispersion, and polarization mode dispersion. Because these mechanisms affect fiber networks in different ways, we’ll discuss each in some depth. Please download the full article for more information.

    Modal Dispersion

    In general, our article on Single-Mode Optical Fiber Selection focuses on single-mode fibers since they comprise the vast majority of fiber kilometers deployed around the world. In contrast to multimode fibers, single-mode fibers are used for all high-capacity, long-distance networks due to their low attenuation and high bandwidth. A main limiting factor of multimode fibers is modal dispersion.

    >> Download the full Article

    Illustration of Modal dispersion in a multimode and single optical fibers

    Multimode fibers carry multiple modes of light at the same time.  While a mode of light can be thought of as a ray of light, a typical multimode fiber can have up to 17 modes of light traveling along it at once. These modes all traverse slightly different paths through the fiber, with some path lengths longer than others. Modes that take a straighter path will arrive sooner, and modes that bounce along the outer edges of the core of the fiber take a longer path and arrive later. The effect on the end pulse is called modal dispersion, since it is due to the different modes in the fiber. Multimode fibers are designed to reduce the amount of modal dispersion with precise control of the index of refraction profile, through the quantity of dopants used in the core. However, it isn’t possible to completely eliminate modal dispersion in multimode fibers.

    Chromatic Dispersion

    Chromatic dispersion describes a combination of two separate types of dispersion, namely material dispersion and waveguide dispersion. Light travels at different speeds at different wavelengths, and all laser pulses are transmitted over a wavelength range. Light also travels at different speeds through different materials. These varying speeds cause pulses to either spread out or compress as they travel down the fiber. Fiber designers can use these two points to customize the index of refraction profile to produce fibers for different applications. Chromatic dispersion isn’t always a bad thing. In fact, it can be used as a tool to help optimize network performance.

    For example, the first lasers used for fiber transmission operated at 1310 nm, and many networks still use that wavelength. Fiber designers therefore developed the first single-mode fibers to have minimum or zero dispersion at this wavelength. In fact, G.652 fibers are still designed this way. In these fibers, dispersion is higher in the 1550 nm window.

    Today’s networks often operate with multiple wavelengths running over them. In these networks, nonlinear effects that result from the multiple wavelengths can affect network operation. We’ll give a brief overview of some of these non-linear effects in this article. Chromatic dispersion is often used as a tool to help optimize these types of networks.

    Polarization Mode Dispersion (PMD)

    Light is an electromagnetic wave and is comprised of two polarizations that travel down the fiber at the same time. In a perfectly round fiber deployed with perfectly balanced external stresses, these polarizations would reach the end of the fiber at the same time. Of course, our world isn’t perfect. Even small amounts of glass ovality/non-concentricity or non-concentric stresses in the cable can cause one of the polarizations to travel faster than the other, spreading out in time as they travel along the fiber. This phenomenon is called polarization mode dispersion (PMD).

    Polarization mode dispersion illustration- delay in two polarizations traveling down an optical fiber.

    Cabling and installation affect PMD, and even things like vibration from trains moving down tracks or wind-induced aerial cable vibrations can affect PMD. However, the impacts of these interactions are typically smaller than the inherent PMD caused by the glass manufacturing process.

    Manufacturing Caused of Polarization Mode Dispersion (PMD)

    There are ways to mitigate PMD. One very effective method is to make the glass fiber as geometrically round and consistent as possible. OFS uses a special technique to accomplish this. Using a patented process called fiber “spinning”; half-twists are translated through the fiber during the draw process, reducing the non-concentricities and ovalities in the glass that are the major contributors to increased PMD.

    PMD Chart

    >> Download the full Article

    Non-Linear Effects

    There are a host of other factors that network, equipment, and fiber designers have needed to consider as network capabilities have grown over the years. These factors often result as we collectively add more and more wavelengths of traffic at greater speeds and higher power levels.

    It is not the intent of this article to review each of these in depth, but instead to touch on them so the reader can have a passing familiarity. The highest profile of these factors is four-wave mixing, which led to the development of non-zero dispersion-shifted fibers (NZDF). However, other non-linear effects include self-phase modulation, cross-phase modulation, Raman and Brillouin scattering, and others. As mentioned earlier, chromatic dispersion can be used to offset the effects of four-wave mixing. For those non-linear effects related to higher power levels, increasing the effective area where the light travels down the fiber can help to reduce the impact of these other non-linear effects.

    Dispersions and non-linear effects are the least understood issues in the general fiber user population, mainly because the guidelines used to match up today’s fibers and electronics typically work so that the end user doesn’t need to have a detailed background to bring up a system.

    OFS has multiple decades of experience with fiber optic networks. Please contact your local OFS representative if you would like additional information regarding any of the items in this article.

    >> Download the full Article

    OFS is a market leader in the design and manufacture of standard and custom Dispersion Slope Compensating Modules (DSCMs) also known as Dispersion Compensating Modules (DCMs). Our fixed broadband, reconfigurable, and tunable colorless modules round out a product line that is well-suited for the major transmission fiber types.

  7. Bandwidth Drivers and Fiber Optic Standards

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    The fiber optic cable world has come a long way over the past 30 years. Products have become more rugged and user friendly, making it easier for people to enter the industry and work handling optical fiber and cable. While this is great for the industry, many people may understand the “how to” but not necessarily the “why” of fiber optics. To understand the “why” behind fiber and cable products, the next step is to become a full-fledged “fiber geek.” Because the industry changes so quickly, it’s important to understand fiber specifications are continuously changing.

    Bandwidth demand continues 

    Enjoying virtual reality technologyThe demand for bandwidth continues unabated, driven by Web 1.0/2.0, mobile and now streaming video. The result is an expected Compound Annual Growth Rate (CAGR) of approximately 22% across the network through 2020.

    While that’s somewhat old news, new bandwidth demand is on the horizon, potentially driven by several relative sources including 4K TV, virtual reality and an expansion of the “Internet of Things.”

    Ultra HD TV, also known as 4K TV, first appeared on the radar screen approximately four to five years ago. While 4K TV offers twice the resolution of standard HDTV, the first models were priced at more than $20,000. Since then, the cost of 4K TV units has dropped rapidly to the point that they are now ubiquitously available at most electronics stores.

    While linear TV packages still don’t offer many 4K programming options, over-the-top video providers such as Netflix and Amazon Video are rapidly adding content.

    The primary reason that 4K TV is significant to bandwidth demand is that each 4K channel requires up to 25 Mbps, more than 2X the typical HD video requirement. Considering the number of TV screens that are typically on in a household, the potential demand could be a significant increase versus current HDTV demand levels.

    High resolution screens are also an integral part of the experience promised by virtual reality. Virtual reality, while in its commercialized early stages, holds the promise of significantly changing the way that we experience media of all types. However, there’s a catch – fully- networked 4K virtual reality will require hundreds of megabits per second (or more) of bandwidth(1).

    High Def TVHigh resolution video will continue to use bandwidth as it becomes embedded in various networked applications such as telemedicine, remote medical monitoring and distance learning.

    Why does optical fiber care?

    This bandwidth demand can be satisfied in three ways: faster electronics, more wavelengths on the fiber and more optical fiber.

    Standards are important

    IOT requires Fiber StandardsFiber optic standards help to ensure a minimal level of network compatibility and performance. The standards-making process is an arduous one. Fiber standards are global, and standards makers strive to achieve balance and fairness. However, standards often provide only minimum performance levels. In fact, fibers that meet the standards may struggle with some current as well as future applications.

    For this reason, it’s best to insist on fiber optic performance beyond the standards for many applications.

    The demand for bandwidth is expected to continue far into the future, driven in part by requirements for breakthrough applications such as higher resolution video, virtual reality and other applications. We expect this demand to continue to drive the need for optical spectrum provided by fiber. Fiber standards, such as G.652 and G.657, are very important for network designers in setting minimum performance levels but can ultimately be insufficient to meet the requirements for future networks. For this reason, performance beyond the standards can be very important.

    >> Download the Full Article

    Reference (1): Why The Internet Pipes Will Burst When Virtual Reality Takes Off

  8. Optical Fiber Building Solutions

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    FTTX Building Optimized Fiber Infrastructure

    Optical fiber-to-the-business deployment is accelerating globally to support increasing internet speeds of up to 1 Gigabit per second, and 10 Gigabit speeds that are already available in some regions. Service providers are responding by installing optical fiber both to and deep inside buildings to the living unit.

    The Solutions in this 64-page guide can help reduce both first and life cycle costs of optical fiber deployments to residential and business customers.

    Solutions for both Greenfield installation during building construction and Brownfield installation in existing buildings are included. Scalable and optimized to fit a broad range of building structures, these solutions offer faster, reliable installation through innovative labor saving technologies, using less space than conventional approaches.

    Solutions for both indoor and outdoor deployment offer flexibility to use the best available pathways for each building. The solution building blocks include a wide range of terminals, splitters, point-of-entry modules, riser cables, attic and wall fish fiber, hallway fiber and complete indoor living unit fiber kits. This portfolio allows service providers to select the best solution for each building, and OFS can help design building specific solutions and bills of material as a value added service.

    >> DOWNLOAD OUR GUIDE NOW

    FIBER TO THE BUILDING BENEFITS 

    OFS fiber-to-the-subscriber (FTTx) solutions help to revolutionize the speed of installing fibers; enhance the customer experience; minimize disruption; reduce labor costs; increase subscriber take rates; enable faster time to revenue for service providers; and get Gigabit and higher speeds faster to subscribers.

    OPTICAL FIBER BUILDING CHALLENGES AND SOLUTIONS 

    • Time to revenue: Fast and easy to install pre-terminated solutions can speed installation and reduce labor costs.
    • No pathways, requiring labor intensive cut and patch: Compact surface mounted fiber solutions.
    • Limited closet space: Smaller enclosures can enable installation of multiple operator connections in a small telecommunications closet.
    • Multiple boxes for splicing and splitter connections: Single box pre-terminated solutions can require less space and enable faster provisioning.
    • No duct space: Compact surface mounted fiber solutions either inside or on the outside of the building do not require duct.
    • Shared infrastructure: Compact cables can support multiple service providers in telecommunication pathways.
    • Fiber bends around many corners: Bend-insensitive fiber specified to support bend radius as low as 2.5 mm.
    • Disruptive/noisy to tenants: Optical solutions that are virtually invisible can be installed quickly and quietly and preserve the building decor.
    • Service disruptions and lost subscribers: Full solution of fiber, cable and connectors from one company, designed to work together. Factory tested to Tier 1 standards.
    • Multiple building types: Solutions to fit each building type.

    PRE-TERMINATED vs. FIELD TERMINATED OPTICAL FIBER

    Pre-terminated solutions are increasingly used to install fiber in Multiple Dwelling Unit (MDU) buildings to save time and money in higher labor cost regions. Pre-terminated products with built-in slack management are preferred so installers can neatly manage excess slack and use a single component to support multiple deployment lengths. Nevertheless, field terminated solutions can complement pre-terminated parts of the indoor or outdoor network and, for low labor cost markets, field terminated solutions may be preferred. OFS offers both pre-terminated and field terminated solutions to fit the needs of each service provider.

    OPTICAL FIBER SPECIFICATIONS OPTIMIZED TO THE APPLICATION

    Installing optical fiber in buildings and homes often requires conforming the fiber around sharp corners. EZ- Bend® Single-Mode Fiber offers outstanding bend performance down to a 2.5 mm radius for the most challenging in-residence and MDU applications. Compatible with the installed base of conventional G.652.D single-mode fibers, the fiber meets and exceeds ITU-T G.657.B3 recommendations. EZ-Bend fiber uses patented, groundbreaking EZ-Bend Optical Technology from OFS to provide three times lower loss at tight bends than competing G.657.B3 products.

    Centralized, Distributed and Distributed Cascaded Splitting

    As FTTx deployment accelerates globally to meet increasing bandwidth needs, service providers must install optical fiber both to and inside the building for business and residential subscribers. Building types include duplexes, garden style, low rise (less than 10 floors), mid rise (10 to 15 floors), high rise (16 to 40 floors) and skyscrapers (40 floors and above). To provide building Gigabit services, providers must place optical cables in building risers and ducts, install optical fiber in hallways, and then take this fiber deep into the units, connecting to an indoor Optical Network Terminal (ONT). How can providers accomplish this in buildings that can vary widely in design, materials and available pathways?

    Splitter Architectures

    Cascaded SplitterA typical PON network consists of the Optical Line Terminal (OLT) in a central office, head end or cabinet, connected by a feeder cable to optical splitters, and then to distribution cables downstream in the network. Choosing the right architecture depends upon end-user density, projected subscription rates and distance from the OLT. Splitter placement is important in FTTx design as it can significantly affect plant and electronics costs.

    Three common types of splitter architectures are used when deploying FTTx:

    • Centralized splitting
    • Distributed splitting
    • Distributed cascaded splitting

    To help meet these needs, the OFS portfolio supports all three splitter architectures, and features a broad range of solutions to meet the requirements of virtually any MDU deployment. For flexibility and regional preferences, these offers include a mix of pre-connectorized, in-field fusion splicing and mechanical connector solutions from which OFS can configure customized designs for each type of building.

    Brownfield Outdoor Facade Solution

    The Outdoor Facade Solution is used when property owners want to preserve the decor of the building exterior. The compact EZ-Bend Indoor/Outdoor cable is placed vertically on the exterior wall of the residence from an outdoor wall mount box to an indoor SlimBox® unit. The indoor SlimBox can be factory configured with SCA adapters or fanouts for a pre-terminated solution, or for fusion splicing. EZ-Bend jumpers are used for the path to each living unit. Pre-terminated EZ-Bend Jumpers are recommended for faster installation, or a mechanical connector may be used for field termination in the SlimBox Wall Plate. The 80×80 InvisiLight® Module can be used as a “fiber extension” to any location in the living unit. Alternatively, instead of EZ-Bend jumpers, the InvisiLight MDU solution may be placed in the hallway to the living units (not shown).

    Brownfield Outdoor Facade Solution

    Brownfield Outdoor Facade Solution

    Greenfield Pre-Terminated Solution

    TELECOMMUNICATION ROOM

    • Compact basement box for a progressive customer activation;
    • The basement box (SlimBox 64F Terminal) allows fusion splices for the outside plant cable;
    • Ideal for buildings with low penetration rates: One splitter can be installed and the management of the customers is done through the SCA ports. A parking area permits easy connection of new customers;
    • Several boxes can be connected for modular expansion. Connections between multiple SlimBoxes are possible through access openings between them.

    RISER BACKBONE

    • SCA pre-terminated cables for quick plug and play installation;
    • EZ-Bend patch cords directly from the apartment unit may be used for small buildings.

    HORIZONTAL DEPLOYMENT

    • Direct deployment from the telecommunication closet to the apartment unit;
    • Ideal for Greenfield installation;
    • The EZ-Bend jumper is connected to an adapter installed in the SlimBox Wall Plate (inside the living unit).

    INSIDE THE LIVING UNIT

    • An SCA mechanical connector can be used to terminate the EZ-Bend Jumper inside the living unit;
    • The InvisiLight ILU Solution is a complementary product used to extend the fiber inside the apartment.

    >> DOWNLOAD OUR GUIDE NOW

    Greenfield Fusion Spliced or Field Terminated Solution

    TELECOMMUNICATION ROOM

    • Compact basement box for a progressive customer activation (parking up to 48 connectors in the SlimBox 64F Terminal);
    • The basement box (SlimBox 64F Terminal) allows fusion splices for the outside plant cable and the internal cables (up to 96 fusion splices – 8 splice trays with 12 splices in each one);
    • Ideal for buildings with low penetration rate: One splitter can be installed with management of the customers done through the SCA ports. A parking area permits easy connection of new customers;
    • Several boxes can be connected for modular expansion. Connections between SlimBoxes are possible through access openings between them.

    RISER BACKBONE

    • ACCUMAX® cables may be used for quick and easy installation:
    • SCA pre-terminated pigtails are used for fusion splicing inside the basement and floor boxes.

    HORIZONTAL DEPLOYMENT

    • Direct deployment from the telecommunication closet to the apartment unit through EZ-Bend cable (ruggedized 3.0 or 4.8 mm);
    • The horizontal cable is fusion spliced or field terminated with a mechanical connector in the SlimBox 12F Terminal (floor distribution box) and in the SlimBox Wall Plate (inside the living unit).

    INSIDE THE LIVING UNIT

    • An SCA mechanical connector can be used to terminate the EZ-Bend Jumper inside the living unit or a pre-terminated pigtail can be used;
    • The InvisiLight ILU Solution is a complementary product used to extend the fiber inside the apartment.

    >> DOWNLOAD OUR GUIDE NOW

    Brownfield Pre-Terminated Solution

    Brownfield Pre-Terminated Solution

    Brownfield Pre-Terminated Solution

    TELECOMMUNICATION ROOM

    • Compact basement box for progressive customer activation;
    • The basement box (SlimBox™ 64F Terminal) allows fusion splices to the outside plant cable;
    • Ideal for buildings with low penetration rate: One splitter can be installed with management of the customers done through the SCA ports. A parking area permits easy connection of new customers;
    • Boxes can be added for modular expansion. Connections between SlimBox units are easily made using jumpers through multiple ports designed into the box.

    RISER BACKBONE

    • SCA pre-terminated cables for quick plug and play installation:
    • It is possible to place InvisiLight 2.0 mm 12-Fiber multifiber cord directly from the basement box and down hallways in small or garden style buildings.

    HORIZONTAL DEPLOYMENT

    • The InvisiLight MDU Point of Entry (POE) Module offers a discrete solution using field termination inside the module;
    • Virtually invisible installation using the InvisiLight 12F Pre-terminated 2.0 mm cord.

    INSIDE THE LIVING UNIT

    • InvisiLight ILU Solution is complementary and connects to the InvisiLight MDU installation;
    • InvisiLight ILU Solution is installed with the same tools and procedures as the InvisiLight MDU Solution

    This 64-page guide with illustrations and part specifications will help in  selecting the right fiber optic cables and accessories to reduce both the first and life cycle costs of fiber deployments to business customers inside buildings.

    >> DOWNLOAD OUR GUIDE NOW

  9. FAQ Guide to Laser-Optimized Fiber

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    As transmission speeds over optical fiber networks in the enterprise increase to 10 Gigabits per second (Gb/s) and beyond, a relatively new term – “laser-optimized fiber” – has crept into the industry’s vocabulary. What is laser-optimized fiber? What do you need to know about it? And what exactly does the term “laser- optimized” mean? Understanding the answers to these questions will help you prepare for the latest wave in optical communications for enterprise networks.Laser Fiber

    Why have optical fibers been “optimized” for use with lasers?

    Older “legacy” optical fiber systems (Token Ring, Ethernet, FDDI, ATM) used in premises applications operated at relatively slow speeds in the range of 4 to 155 Megabits per second (Mb/s). These systems utilized inexpensive light sources called Light Emitting Diodes (LEDs), which were perfectly adequate for these slower speeds. Multimode fibers used in these systems were rated to certain minimum bandwidths, typically:

    • 160 MHz/km over 62.5/125 μm fiber at 850 nm
    • 500 MHz/km over 50/125 μm fiber at 850 nm
    • 500 MHz/km over both products at 1300 nm

    These fibers were tested for bandwidth using an Overfilled Launch (OFL) test method, which accurately replicated real-life performance with an LED.

    As the demand for bandwidth and higher throughput increased, especially in building and campus backbones, LEDs could not keep pace. With a maximum modulation rate of 622 Mb/s, LEDs would not support the 1 Gb/s and greater transmission rates required. One could make use of traditional lasers (Fabry-Perot, Distributed Feedback) typically used over single-mode fiber.  However these are considerably more expensive due to the higher performance characteristics required for long-distance transmission on single-mode fiber.

    In response, the industry developed a new high-speed laser light source called a Vertical Cavity Surface Emitting Laser (VCSEL). These VCSELs are inexpensive and well suited for low-cost 850 nm multimode transmission systems, allowing for data rates of 1 Gb/s and 10 Gb/s in the enterprise. With the emergence of these VCSELs, multimode fiber had to be “optimized” for operation with lasers.

    >> Download Our Guide Now

    What’s the Difference Between a VCSEL and an LED?

    VCSELs provide higher power, narrower spectral width, smaller spot size and faster data rates than LEDs. All of these advantages add up to a significant performance boost. This assumes, of course, the fiber itself does not hinder performance. To understand why this could occur, we need to recognize the differences between VCSELs and LEDs and how they transmit signals along a multimode fiber.

    All LEDs produce a smooth, uniform output that consistently fills the entire fiber core and excites the many hundreds of modes in the fiber. The bandwidth of the fiber is determined by the aggregate performance of all the modes in the fiber. If a few modes lag behind or get ahead due to modal dispersion, they have little impact on bandwidth because many other modes are carrying the bulk of the signal.

    The energy output of a VCSEL is smaller and more concentrated than that of an LED. As a result, VCSELs do not excite all the modes in a multimode fiber, but rather only a restricted set of modes. The bandwidth of the fiber is dictated by this restricted set of modes, and any modes that lag or get ahead have a much greater influence on bandwidth.

    Typically, a VCSEL’s power would be concentrated in the center of the fiber, where older fibers were prone to defects or variations in the refractive index profile (the critical light-guiding property in the core of the fiber), resulting in poor transmission of the signal. That is why some fibers may actually perform poorly with a VCSEL compared to an LED.

    To complicate matters, the power profile of a VCSEL is nonuniform and fluctuates constantly. It changes sharply across its face, varies from VCSEL to VCSEL and changes with temperature and vibrational fluctuations. Consequently, individual VCSELs will excite different modes in a certain fiber at any given time. And because different modes carry varying amounts of power, the fiber’s bandwidth can vary in an unpredictable manner.

    Why are laser-optimized fibers the best choice for use with VCSELs?

    With the advent of VCSELs, it became apparent that the traditional multimode fiber deployed for LED systems did not take full advantage of the performance benefits of VCSELs.

    To fully capitalize on the benefits that VCSELs offered, fiber manufacturers developed laser-optimized multimode fiber (LOMMF). LOMMF is specifically designed, fabricated and tested for efficient and reliable use with VCSELs.

    LOMMFs should have a well-designed and carefully controlled refractive index profile to ensure optimum light transmission with a VCSEL. Precise control of the refractive index profile minimizes modal dispersion, also known as Differential Mode Delay (DMD). This ensures that all modes, or light paths, in the fiber arrive at the receiver at about the same time, minimizing pulse spreading and, therefore, maximizing bandwidth. A good refractive index profile is best achieved through DMD testing.

    VCSELs and LOMMF provide tremendous flexibility and cost efficiency in “freeing up” bandwidth bottlenecks in the enterprise today and well into the future. LOMMF is completely compatible with LEDs and other fiber optic applications (there are no special connectors or termination required and no effect on attenuation). LOMMF can be installed now and utilized at slower data rates until the need arises to increase network speed to 1 or even 10 Gb/s. At that point, you only need to upgrade the optics modules to VCSEL-based transceivers. There is no need to pull new cable.

    >> Download Our Guide Now

    Can you use any laser-optimized fiber for 10 Gb/s?

    No — it is important to note that not all laser-optimized fiber is 10 Gb/s capable. If 10 Gb/s capacity is in your future, you must make sure that the LOMMF you’re installing now is capable of handling 10 Gb/s. The first laser-optimized fibers, introduced to the market in the mid-1990s, were designed for 1 Gb/s applications. Available in both 62.5/125 µm and 50/125 µm designs, these fibers extended the reach capability of 1 Gb/s systems beyond what the industry standards stated. For instance, OFS 1 Gb/s Laser Optimized 62.5 Fiber can go 300 meters in cost-effective, 1 Gb/s 850 nm (1000BASE-SX) systems. 50/125 µm fibers offer even greater performance, with a reach of 600 meters or more. These 1 Gb/s LOMMFs, coupled with 850 nm VCSELs, allow for the lowest systems cost for building backbones and short-to medium-length campus backbones

    How do you measure bandwidth for laser-optimized fiber?

    Since LEDs have a uniform and consistent power profile that excites all the modes in a multimode fiber, the traditional OFL method of bandwidth measurement accurately predicts bandwidth of fiber for LED applications. But because VCSELs only excite some of the modes in a fiber, and in a varying manner, the OFL bandwidth measurement cannot predict what the fiber’s bandwidth would be if the fiber were to be used in a VCSEL application.

    It should become clear now why fiber manufacturers developed laser-optimized fiber, and why DMD testing is so important. The refractive index has to be well designed and controlled to ensure that all modes exhibit minimal DMD and all arrive at the other end of the fiber at the same time. No matter which modes in the fiber are actually guiding the light, those modes will have minimal DMD and provide high bandwidth.

    What should you look for in DMD testing?

    DMD testing provides a clear picture of how individual mode groups carry light down the fiber, and which mode groups are causing DMD. In fact, that picture is so clear that the standards require fiber to be DMD-tested to ensure adequate bandwidth to the rated distances for 10 Gb/s applications.

    >> Download Our Guide Now

    Tony Irujo is sales engineer for optical fiber at OFS, a world-leading designer, manufacturer and provider of optical fiber, fiber optic cable, connectivity, fiber-to-the-subscriber (FTTx)and specialty photonics products. Tony provides technical sales and marketing support for multimode and single-mode optical fiber.

    Tony has 25 years of experience in optical fiber manufacturing, testing and applications. He started with SpecTran in 1993 as a quality and process engineer and transitioned to more customer-focused roles with Lucent and OFS. He represents OFS in the Fiber Optic LAN Section (FOLS) of the TIA, has authored several papers on fiber technology and applications and is a frequent speaker at industry events. Tony has a Bachelor of Science degree in Mechanical Engineering from Western New England College in Springfield, MA.

  10. Fiber Optic Solutions for Fiber to the Home (FTTH)

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    A Fiber to the Home Diagram

    Fiber to the Home (FTTH) is becoming increasingly more common as bandwidth usage is exploding. This tremendous growth is driven in part by the rapid increase in Internet-connected devices and the use of data-heavy applications such as video on demand. Service providers are working to meet this need for greater bandwidth by expanding the deployment of fiber optic cables to the premises and then into the home.

    Service providers building these fiber networks all face a common challenge: the expense of the last mile in the optical network. It is critical for service providers, utilities and municipalities to have an optimized set of deployment options that help to reduce both capital and operational expenses.

    The solutions presented in this article meet these challenges with several fiber deployment options from the drop point to and into the home.

    OFS FTTx Solutions for the Home can help residents take advantage of the Internet of Things (IoT), which is beginning to redefine how we work and live. These solutions focus on simplicity, cost-effectiveness and speed of installation, along with the pre- and post-installation customer experience, time to revenue generation and reliable subscriber connections that help to improve profitability for the service provider.

    FTTH is considered the best technology to handle consumer network demands in the future because of its high bandwidth.

    >> Download the Full Guide Now

    PRE-TERMINATED vs. FIELD-TERMINATED DROPS

    Pre-terminated drop solutions are increasingly used to install fiber to homes to save time and money in higher labor cost regions. Pre-terminated drop solutions consist of drop cables that are terminated and tested in the factory, and easily plugged into the drop terminal and home terminal in the field. Pre-terminated solutions offer lower costs and faster deployment and require less installation skill.

    For low labor cost markets, field terminated solutions may be preferred. Field terminated solutions use drop cables which are terminated using fusion splicing or mechanical connectors in the field during installation. They offer easier inventory management, lower material costs and easier slack management, but take longer to install and require more highly skilled labor, along with expensive field termination tools and splicing machines, when compared to pre-terminated solutions.

    A third approach, with one end of the drop cable pre-terminated, and the other end field terminated, can solve the slack issue and allow an easy plug-in to the drop terminal and field termination at the home.

    OFS offers all three of these drop solution options to fit the unique needs of each service provider. OFS pre-terminated solutions are available with EZ- Bend® cables that can solve the slack management challenge. EZ-Bend fiber optic cables enable the slack to be tied into a very compact bundle.

    Providers typically use a combination of aerial and underground solutions to connect the last mile in a network to individual homes. A variety of factors including climate and existing infrastructure can influence solution selection.

    >> Download the Full Guide Now

    CONNECTING OPTICAL FIBER TO THE HOME

    OFS offers a complete portfolio of aerial and underground solutions including terminals, integrated splitters and drop cables to connect to the demarcation point of individual homes. From that location, a number of solutions can be leveraged to take optical fiber into the home.

    FTTH Aerial InstallationAerial deployment is typically lower in cost and preferred where poles are in place near homes. In this scenario, a SlimBox® Drop Terminal is installed on a pole, with or without splitters, and then connected by a drop cable to as many as 16 homes. Below grade drop deployment is preferred if there is an existing duct placed from the terminal location to the home, or if below grade cabling is required by local regulations.

    First, an installer inserts a feeder or distribution cable into the terminal. The installer then extracts the number of fibers required and fusion splices them to a pre-terminated splitter or drop fiber. Aerial or underground drop cables are then deployed from the terminal to individual residences.

    In the case of aerial cables, a drop cable is placed between the pole and a point near a home’s roof. The cable can be connected to a demarcation box and installed into the home through the attic or onto the side of the house at a demarcation box near the ground. To help avoid unsightly aerial cables, an aerial terminal can be connected to an underground drop cable. For aerial deployments, OFS offers the one to 24-fiber Mini LT Flat Drop Cable and the single-fiber Mini TB Flat Drop cable which contains 3 mm cordage that can be routed directly to an Optical Network Terminal (ONT).

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    Fiber to the Home Underground Installation IllustrationUnderground drop cable options include the single-fiber EZ-Bend® 3.0 mm and 4.8 mm Ruggedized Cables and EZ-Bend Toneable Cables. The toneable cables enable easy above ground locating of buried cables to help avoid cable cuts when other underground systems are installed. These drop cables are installed from the aerial terminal down the pole to the ground, and are then buried to minimize disruption to landscaping, or pulled into existing duct. The cable is then connected into a demarcation box installed at the side of the house, ideally in a location close to the ONT on the inside.

    EZ-Bend cables are preferred since their 2.5 mm bend radius allows the cables to be coiled, bent and tied without creating signal degradation. These cables can also be buried or stapled/clipped and bent around the outer perimeter walls of a home to reach an entry point closer to the preferred ONT location.

    New home construction offers a win-win situation for construction companies and service providers. With the ability to “build in” optical fiber connectivity, new homes are futureproofed from the beginning, real estate values increase, and new home owners can become immediate subscribers without the expense of additional installation time. .

    Subscribers can be connected faster using preterminated cables installed to and into homes during construction. OFS offers EZ-Bend 3.0 mm and 4.8 mm cables that can be installed independently or in ducts using typical home wiring techniques, such as stapling or zip-tying of the cables, to a location or media panel where the ONT would be later placed. The home owner can later perform a “self install” by receiving an ONT from the service provider, and simply plugging in an EZ-Bend cable assembly and a power adapter to the ONT. OFS also provides a SlimBox Wall Plate that discretely blends into a home’s décor and facilitates ONT connections in the same way as a power outlet.

    Existing Homes can pose a challenge to network installers, given the wide variety of possible building architectures. In addition, home designs and construction materials can vary greatly from country to country and even within countries. OFS solutions are purposefully designed and optimized to suit a variety of homes globally and offer maximum flexibility to on-site installers.
    Depending on the target market, a provider can choose the terminals and drop cables for an aerial, underground or hybrid solution. The solutions described are the most popular options and feature a variety of products as building block components. This modular product design approach allows service providers to also create custom solutions to meet the specific needs of their target markets.

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