Most Popular Articles

• How to Install or Remove SFP Transceiver Modules on Cisco Device

  Feb 7, 2016 by Articles / 747 Views

  The SFP (small form Factor pluggables) transceiver modules are hot-pluggable I/O devices that plug into module sockets. The transceiver connects the electrical circuitry of the module with the optical or copper network. SFP transceiver modules are the key components in today's transmission network. Thus, it is necessary to master the skill of installing or removing a transceiver modules to avoid unnecessary loss. This tutorial are going to guide you how to install or remove SFP transceiver module in a right way.

   

  Things you should Know Before Installing or Removing SFP

  Before removing or installing a Transceiver Module you must disconnect all cables, because of leaving these attached will damage the cables, connectors, and the optical interfaces. At the same time please be aware that do not often remove and install an SFP transceiver and it can shorten its useful life. For this reason transceivers should not be removed or inserted more often than is required. Furthermore, transceiver modules are sensitive to static, so always ensure that you use an ESD wrist strap or comparable grounding device during both installation and removal.

   

  Required Tools

  You will need these tools to install the SFP transceiver module:
  Wrist strap or other personal grounding device to prevent ESD occurrences.Antistatic mat or antistatic foam to set the transceiver on.Fiber-optic end-face cleaning tools and inspection equipment

   

  Installing SFP Transceiver Modules

  SFP transceiver modules can have three types of latching devices to secure an SFP transceiver in a port socket:
  SFP transceiver with a Mylar tab latch.SFP transceiver with an actuator button latch.SFP transceiver that has a bale-clasp latch.

  

  Determine which type of latch your SFP transceiver uses before following the installation and removal procedures.

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• Migrate to a 40-Gbps Data Center with Cisco QSFP BiDi Technology

  Apr 23, 2018 by Cisco Channel / 702 Views

  What You Will Learn

  This document describes how the Cisco^® 40-Gbps QSFP BiDi transceiver reduces overall costs and installation time for customers migrating data center aggregation links to 40-Gbps connections.

  As a result of data center consolidation, server virtualization, and new applications that require higher data transport rates, the data center network is shifting to 10 Gbps at the access layer and 40 Gbps at the aggregation layer. A broad portfolio of high-performance and high-density 10- and 40-Gbps Cisco Nexus^® Family switches is available at attractive prices for this transition. However, to support 40-Gbps connectivity, data center architects are challenged by the need for a major upgrade of the cabling infrastructure, which can be too expensive or disruptive to allow data centers to quickly adopt and migrate to the 40-Gbps technology.

  Cisco solves this problem with innovative 40-Gbps Quad Small Form-Factor Pluggable (QSFP) bidirectional (BiDi) technology that allows reuse of existing 10-Gbps fiber infrastructure for 40-Gbps connections.

  Challenges with Existing 40-Gbps Transceivers

  Standard short-reach (SR) 10- and 40-Gbps transceivers use fundamentally different connectivity formats, requiring fiber cabling infrastructure to be redesigned and replaced. 10-Gbps SR transceivers operate over dual-fiber multimode fiber (MMF) with LC connectors, and 40-Gbps SR protocols, such as SR4 and CSR4, operate over MMF ribbon with MPO connectors. As a result, 40-Gbps MPO-based SR4 transceivers cannot reuse aggregation fiber infrastructure built for 10-Gbps connectivity.

  Connector type is not the only concern. Whereas 10-Gbps SR transceivers require 2 fiber strands per 10-Gbps link, 40-Gbps SR4 and CSR4 transceivers require a theoretical minimum of 8 fiber strands, and often 12 fiber strands in practice. The reason for this requirement is that 40-Gbps SR4 and CSR4 use 4 parallel fiber pairs (8 fiber strands) at 10-Gbps each for a total of 40-Gbps full duplex, as shown in Figure 1. However, both use MPO-12 connectors, which terminate 12-fiber ribbons. As a result, 4 fiber strands in each connection are unused and wasted.

  To economize trunk fiber in a structured cabling environment, a 2 x 3 MPO fiber conversion module could combine three SR4 links onto two 12-fiber ribbon cables. But even then the 40-Gbps SR4 trunk still uses 8 fiber strands per link compared to 2 fiber strands in the case of 10-Gbps SR.

  At best, the connector change and increased fiber density needed for SR4 require a significant cable plant upgrade, making it expensive and disruptive for customers to migrate from 10-Gbps connectivity to 40‑Gbps connectivity in their existing data centers.

  Figure 1.      Concept of Existing 40-Gbps Transceivers: Of the 12 Fiber Strands Terminated by MPO-12 Connectors, 8 Fiber Strands (4 Fiber Pairs) Carry Traffic and 4 Are Unused

   

  Solution with Cisco 40-Gbps QSFP BiDi Transceiver

  The Cisco QSFP BiDi transceiver, shown in Figure 2, transmits full-duplex 40-Gbps traffic over one dual-fiber LC-connector OM3 or OM4 MMF cable. It provides the capability to reuse 10-Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40-Gbps connectivity without making any changes to the previous 10-Gbps fiber cable plant.

  Figure 2.      Cisco QSFP BiDi Transceiver (QSFP-40G-SR-BD)

   

  The Cisco QSFP BiDi transceiver has two 20-Gbps channels, each transmitted and received simultaneously over two wavelengths on a single MMF strand. The result is an aggregated duplex 40-Gbps link over a MMF duplex LC-terminated fiber cable. The connection can reach 100 meters on OM3 MMF or 150 meters on OM4 MMF, which is the same as 40-Gbps SR4. Figure 3 shows the technology concept of the Cisco QSFP BiDi transceiver.

  Most Cisco switching and routing products that support 40 Gigabit Ethernet interfaces support the Cisco QSFP BiDi transceiver. For a complete list of supporting products, refer to the Cisco 40 Gigabit Optical Transceiver product page at http://www.cisco.com/en/US/products/ps11708/index.html.

  Figure 3.      Concept of Cisco QSFP BiDi Transceiver

   

  Savings with Cisco QSFP BiDi When Migrating from 10 Gbps to 40 Gbps

  This section presents two case studies that demonstrate the savings achieved by using Cisco QSFP BiDi technology for 40-Gbps connectivity in data center networks. The case studies show how Cisco QSFP BiDi technology can remove the cost barriers for migrating and expanding the existing 10-Gbps cabling footprint to 40-Gbps infrastructure to provide the higher data rate in the data center network.

  Case Study 1: 288 x 40-Gbps Connections with Unstructured Cabling

  In an unstructured cabling system, devices are connected directly with fiber cables. This direct-attachment design can be used to connect devices within short distances in a data center network. As shown in Figure 4, direct connection between two 40-Gbps devices can be provided by MMF cables with either QSFP SR4 or QSFP BiDi transceivers at two ends.

  Figure 4.      Direct 40-Gbps Connections

   

  The QSFP SR4 transceiver uses MPO-12 connectors, whereas Cisco QSFP BiDi uses LC connectors. Existing 10-Gbps connections commonly are MMF cables with LC connectors. Therefore, with QSFP SR4 transceivers, none of the existing 10-Gbps MMF cables can be reused because the connector types are different. Cisco QSFP BiDi allows cable reuse, resulting in zero-cost cabling migration from direct 10-Gbps connections to direct 40-Gbps connections.

  Table 1 summarizes the costs and savings of migration and new deployment of 288 direct connections. To migrate the existing 288 10-Gbps connections to 40-Gbps connections, Cisco QSFP BiDi does not require any new spending on cables. Therefore, in comparison to QSFP SR4 transceivers, Cisco QSFP BiDi transceivers reduce costs by 100 percent and provide savings of up to US$290 per 40-Gbps port.

  Table 1.       Fiber Infrastructure Savings for 10-Gbps to 40-Gbps Direct-Cabling Migration and New 40-Gbps Deployment

  Fiber Cable Infrastructure Cost and Savings with BiDi* (US$)		30m	60m	100m
  288 LC-connector dual-fiber MMF cables for Cisco BiDi		$7,884	$12,966	$19,647
  288 MPO-connector ribbon-fiber MMF cables for SR4		$32,058	$53,562	$83,412
  10-Gbps to 40-Gbps migration	Total savings (US$)	$32,058	$53,562	$83,412
  	Per port savings (US$)	$111	$186	$290
  	Savings (percent)	100%	100%	100%
  New 40-Gbps deployment	Total savings (US$)	$24,174	$40,599	$63,765
  	Per-port savings (US$)	$84	$141	$221
  	Savings (percent)	75%	76%	77%

  ^* This example is based on real-world cable cost estimates. The transceiver cost is not included.

  For the case in which 288 new direct 40-Gbps connections are needed in addition to the existing cabling infrastructure for a data center migration or expansion, the savings for 288 new connections using Cisco QSFP BiDi instead of QSFP SR4 transceivers is as high as 77 percent and US$221 per 40-Gbps port. These numbers do not take into account the installation costs. Adding installation costs could easily double the SR4 deployment costs.

  Case Study 2: 384 x 40-Gbps Connections with Structured Cabling

  A structured cabling system is commonly deployed in data center networks to provide flexible and scalable cabling infrastructure. Structured cabling uses short patch cords to attach devices to a patch panel and then runs fiber trunks either to consolidate the cables in a central location for additional connectivity or to direct them to another patch panel to which the remote devices are attached. Figure 5 shows a simple example of a 10-Gbps structured cabling design.

  Figure 5.      Simple Example of 10-Gbps Structured Cabling

   

  For migration of a data center with a structured 10-Gbps cabling system, Cisco QSFP BiDi technology allows you to repurpose the existing cabling system - including the patch cables, patch panels with MTP/MPO LC modules, and fiber trunks - for 40-Gbps connectivity. In contrast, QSFP SR4 transceivers require new patch cables and patch panels because the connector types differ and the size of the fiber trunk needs to be quadrupled.

  This case study examines a simple nonblocking two-tier fabric design (Figure 6) that provides 1536 10-Gbps edge ports on its leaf layer. Its spine layer is composed of two Cisco Nexus 9508 Switches, and its leaf layer consists of 32 Cisco Nexus 9396PX Switches, each with six 40-Gbps links to every spine Cisco Nexus 9508. There are 384 40-Gbps links total between the leaf and spine layers.

  Figure 6.      Two-Tier Network Example

   

  If 384 x 10-Gbps connections are to be reused to construct this network, no additional spending on cabling will be needed if Cisco QSFP BiDi transceivers are used for all the 40-Gbps links. This scenario thus offers a 100 percent cost savings compared to the cost of reconstructing the cabling system using QSFP SR4 transceivers, including the cost of new patch cables, new patch panels, and expansion of the current fiber trunk.

  If the cabling for this network is a new (greenfield) deployment or an expansion of an existing cabling system, the 384 x 40-Gbps connections can be built by using MMF cables and either QSFP SR4 transceivers or Cisco QSFP BiDi transceivers. Figures 7 and 8 show design examples for each option. Table 2 compares real-world cost estimates for these two designs. The design with Cisco QSFP BiDi offers 77 percent savings over that with QSFP SR4 transceivers, which is equivalent to a savings of US$2077 per 40-Gbps connection.

  Figure 7.      Structured 40-Gbps Cabling with QSFP SR4 Transceivers

   

  Table 2.       Structured 40-Gbps Cable Infrastructure Cost Comparison

  Structured 40-Gbps Cable Infrastructure Cost Savings with BiDi Technology (US$)
  	Unit Price* (US$)	Quantity	Total (US$)
  90m 12-fiber MPO-MPO trunk cable (3 SR links per 2 cables)	$1844	384 x (2/3)	$472,064
  12-fiber MPO-MPO 2x3 conversion module (3 SR links per module, both ends)	$1200	384 x (1/3) X 2	$307,200
  12-fiber MPO jumper (1 per link, both ends)	$340	384 x 2	$261,120
  SR total			$1,040,384
  90m 12-fiber MPO-MPO trunk cable (6 BiDi links per cable)	$1844	384 x (1/6)	$118,016
  12-fiber MPO-LC trunk module (6 BiDi links per module, both ends)	$525	384 x (1/6)	$67,200
  12-fiber LC jumper (1 per link, both ends)	$75	384 x 2	$57,600
  BiDi total			$242,816
  Total savings			$797,568
  Percentage savings			77%

  ^*Based on manufacturer’s list price

  Figure 8.      Structured 40-Gbps Cabling with Cisco QSFP BiDi Transceivers

   

  Conclusion

  Cisco QSFP BiDi technology removes 40-Gbps cabling cost barriers for migration from 10-Gbps to 40-Gbps connectivity in data center networks. Cisco QSFP BiDi transceivers provide 40-Gbps connectivity with immense savings and simplicity compared to other 40-Gbps QSFP transceivers. The Cisco QSFP BiDi transceiver allows organizations to migrate the existing 10-Gbps cabling infrastructure to 40 Gbps at no cost and to expand the infrastructure with low capital investment. Together with Cisco Nexus 9000 Series Switches, which introduce attractive pricing for networking devices, Cisco QSFP BiDi technology provides a cost-effective solution for migration from 10-Gbps to 40-Gbps infrastructure.

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• Fiber Media Converter Tutorial

  Feb 8, 2016 by Articles / 636 Views

  Fiber media converter is a cost-effective solution to overcome the bandwidth and distance limitations of traditional network cable. It dramatically increases the bandwidth and transmission distance of the local area network (LAN) by allowing the use of fiber and integrating new equipment into existing cabling infrastructure. To better understand it, this article will give an overview of fiber media converter.

  What is Fiber Media Converter?

  Fiber media converter is a transfer media that connects two dissimilar media types. Generally, it is a device that converts electrical signal used in copper unshielded twisted paired (UTP) network cabling into light waves used in fiber optic cabling, and vice versa. This kind of fiber media converter is called copper-to-fiber media converter that provides a simple way to introduce fiber into a LAN without tearing out the existing copper wiring or making changes to copper-based switches. Furthermore, there is another kind of fiber media converter that supports fiber-to-fiber conversion, which provides connections between dual-fiber and single-fiber or between multimode fiber and single-mode fiber. Fiber-to-fiber media converters also provide a cost-effective solution for wavelength conversion in Wavelength Division Multiplexing (WDM) applications, which are also known as transponders.

  Types of Fiber Media Converters

  There are a wide variety of fiber media converters available in the market. According to different criteria, fiber media converters may be classified into different types.

  Managed VS Unmanaged

  The managed fiber media converter has the functions of networking monitoring, fault detection and remote management. It helps the network administrator to easily monitor and manage the network. An unmanaged fiber media converter, however, allows for simple communication with other devices and does not have the monitoring and management functions that managed fiber media converter has.

  Platform: Stand-Alone VS Modular Chassis-Based

  According to the platform type, fiber media converters can be divided into stand-alone fiber media converter and modular chassis-based fiber media converter. Stand-alone fiber media converters are designed to be used in where a single or limited number of converter(s) need(s) to be quickly implemented. Modular chassis-based fiber media converters, however, are used in high-density applications that multiple points of copper and/or fiber integration are essential.

  Copper-to-Fiber Media Converter VS Fiber-to-Fiber Media Converter

  According to media types, fiber media converters may be classified into copper-to-fiber media converter and fiber-to-fiber media converter.

  Copper-to-Fiber Media Converter

  Copper-to-fiber media converters are the key to integrating fiber into a copper infrastructure. According to different applications, copper-to-fiber media converters may be further divided into Ethernet copper-to-fiber media converters, video-to-fiber media converters and serial-to-fiber media converters.

  

  Ethernet Copper-to-Fiber Media Converter

  This kind of fiber media converter supports the IEEE 802.3 standard and provides connectivity for Ethernet, fast Ethernet, Gigabit and 10 Gigabit Ethernet devices. SC to RJ45 media converters, SFP to RJ45 media converters, PoE media converters, mini media converters and industrial media converters are all among this type.

  

  The SC to RJ45 media converter comes with RJ45 and SC ports, which is designed to be used with fiber cable preterminated with the SC-type connector.The SFP to RJ45 media converter comes with RJ45 and pluggable fiber optics ports, which allows for flexible network configurations using SFP transceivers. PoE media converters can transparently connect copper to fiber while providing Power-over-Ethernet (PoE) to standards-based PoE compliant devices such as IP cameras, VoIP phones and wireless access points. Mini media converter is a miniature-sized copper-to-fiber converter. It is ideal for bringing fiber to the desktop and for mobile applications where light weight, compact size and low power are required.Industrial media converters are compact and robust devices designed to convert Gigabit Ethernet or Fast Ethernet networks into Gigabit or Ethernet fiber optic networks.

   

  Video Copper-to-Fiber Media Converter

  Video copper-to-fiber media converter also called fiber optic multiplexer, which is used to transmit and receive signals such as video, audio, data and Ethernet. fiber optic multiplexers are devices that process two or more light signals through a single optical fiber (as shown in the following figure), increasing the amount of information that can be carried through a network. Since signals may be analog or digital, video copper-to-fiber can be further divided into converters transmitting analog signals and converters transmitting digital signals. As the name applies, converters transmitting analog signals give amplitude or frequency modulation of the electric signal and then convert it into optical signal. Demodulation will also be done at the receiving end. Converters transmitting digital signals, however, digitize and multiplex the video, audio and data signals, transforming multiple low-speed digital signals into one high-speed signal. This high speed signal will then be turned into optical signal transmitting on a fiber.

  

  In accordance with different applications, there are three commonly used video copper-to-fiber media converters: plesiochronous digital hierarchy (PDH) multiplexers, synchronous digital hierarchy (SDH) multiplexers and synchronous plesiochronous sigital hierarchy (SPDH) multiplexers. Using the PDH fiber transmission technologies, PDH multiplexers are E1 point-to-point optical transport equipment. And the general transmission capacity of this kind of multiplexer is 4E1，8E1 and 16E1. SDH multiplexers, having a large transmission capacity, are designed to support end-to-end provisioning and management of services across all segments of the optical network. SPDH multiplexers adopt both PDH and SDH technologies. It is a PDH transmission system that based on the PDH code speed adjustment principle at the same time, use as far as possible parts of the SDH network technology.

  Serial-to-Fiber Media Converter

  This kind of media converter provides fiber extension for serial protocol copper connections. It accepts serial data on one port in RS232, RS485 or other format and convert the serial data stream into a fiber optic signal to a matching unit at the other end of the fiber span.

  

  Fiber-to-Fiber Media Converter

  Fiber-to-fiber media converters are used to extend network distance by providing connectivity between multimode and single-mode fiber, between different “power” fiber sources and between dual fiber and single-fiber. Furthermore, they also support conversion from one wavelength to another. Mode converter and WDM OEO transponder are two common types of fiber-to-fiber media converters.

  Mode Converter

  A mode converter can be used to allow for an adiabatic transition between two optical modes. Other than cross-connecting different fiber types, mode converters can also re-generate optical signals, extending transmission distance and double fiber cable usage. It is usually applied in multi-mode to single-mode fiber conversion.

  

  WDM OEO Transponder

  When a fiber media converter is used in the WDM system, it is called WDM OEO transponder which converts the incoming signal from the end or client device to a WDM wavelength. WDM OEO transponders are often used for dual fiber to single fiber conversion and wavelength conversion.

  Networks may require conversion between dual and single-fiber, depending in the type of equipment and the fiber installed in the facility. The following figures shows the role of WDM transponder played in the fiber optic network.

  

  WDM OEO transponders are capable of wavelength conversion by using small form-factor pluggable (SFP) transceivers that transmit different wavelengths, provide a cost-effective solution to convert from standard optical wavelengths (850nm, 1310nm and 1550nm) of legacy equipment to optical wavelengths specified for WDM networks.

  

  Selection Guide of Fiber Media Converters

  A proper fiber media converter may provide a cost-effective solution for extending Ethernet transmission while reducing cable and labor cost. When selecting fiber media converters for your network, the following points should be taken into consideration:

  The chip of the fiber media converter shall work in both full-duplex and half-duplex systems. The reason is that some N-Way Switches and HUBs may use half-duplex mode operations, and serious collision and data loss may be caused if the fiber media converter only supports full-duplex operation. Connection test should be done between the fiber media converter and different optical fiber splices. Otherwise, data loss and unstable transmission may happen on account of incompatibility between different fiber media converters.To ensure the proper operation of the fiber media converter, temperature measurement is also necessary. This is because the fiber media converter may not work correctly in high-temperature environment. Thus, it is important to know exactly its working temperature.Safety device guarding against data loss shall be equipped in the fiber media converter.The fiber media converter shall meet the IEEE802.3 standards. If not, there must be a risk of incompatibility.

   

  For a selection of Compufox fiber media converters, please click on the link below:

   

  • Fiber Media Converters

   

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• Fiber Optic Overview

  Feb 6, 2016 by Articles / 631 Views

  Fiber Optic Communication - The Future Of Networking & Data Transmission

  Fiber optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information.

  First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks. Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. Researchers have reached internet speeds of over 100 petabits per second using fiber-optic communication.

  Fiber's advantages has led to its use as the backbone of all of today's communications, telecom, Internet, CATV, etc. - even wireless, where towers are connected on fiber and antennas are using fiber up the towers.

  

   

  Optical Fiber - The Better Solution

  

  This photo from the infancy of fiber optics (to the right) was used to illustrate that one tiny optical fiber could carry more communications signals than a giant copper cable. Today one single mode fiber could carry the same amount of communications as 1000 of those old copper cables!

  Fiber offers thousands of times more bandwidth than copper cables and can go more than 1000 times further before needing repeaters - both of which contribute to the immense economic advantage of fiber optics over copper. You can do a similar analysis for using wireless transmission also, but wireless is limited by the available wireless spectrum which is overcrowded because of everyone's desire to use more mobile devices.

  Why Convert From Copper Cable To Fiber Optic Cable?

  If you need some convincing before you make your first fiber optic cable purchase keep the following facts in mind.

  Optical Fiber - Much More Efficient & Secure

  Fiber optic cable operates much more efficiently and is more secure than traditional copper cabling. Fiber can transmit far more information over greater distance and with a higher clarity while offering a more secure connection. Fiber optic cable is resistant to electromagnetic interference and generates no radiation of its own. This point is important in locations where high levels of security must be maintained. Copper wire radiates energy that can be monitored. In contrast, taps in  Fiber optic cable  Fiber  are easily detected. Copper cable, is also subject to problems with attenuation, capacitance, and crosstalk.

  Optical Fiber - Does Not Require Grounding

  Since fiber is made of glass, which is a bad electrical conductor, it does not require grounding and shields itself from other electrical interference. Fiber cables can be run near electrical cables without fear that it will weaken or interrupt the signal.

  Optical Fiber - Corrosion Resistant

  Fiber optic cable does not corrode and is not as sensitive to water or chemicals. This means you can safely run fiber cable in direct contact with dirt or in close proximity to chemicals (with the proper outer jacket materials).

  Optical Fiber - The Safer Choice

  Since fiber is not a good conductor of electricity, an installer or user will be safe from electrocution if there is a break in the outer jacket and the fiber is exposed.

   

  How Fiber Optic Communication Works

  The process of communicating using fiber-optics involves the following basic steps: Creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal.

  Fiber (or fibre) consists of a strand of pure glass a little larger than a human hair. Fiber optic cable employs photons and pulsing laser light for the transmission of digital signals. Photons pass through the glass with negligible resistance. As light passes through the cable, its rays bounce off the cladding in different ways as shown below. The optic core of fiber optic cable is pure silicon dioxide. The electronic 1s and 0s of computers are converted to optically coded 1s and 0s. A light-emitting diode on one end of the cable then flashes those signals down the cable. At the other end, a simple photodetector collects the light and converts it back to electrical signals for transmission over copper cable networks.

  

  Step index multimode was the first fiber design but is too slow for most uses, due to the dispersion caused by the different path lengths of the various modes. Step index fiber is rare - only POF uses a step index design today.

  Graded index multimode fiber uses variations in the composition of the glass in the core to compensate for the different path lengths of the modes. It offers hundreds of times more bandwidth than step index fiber - up to about 2 gigahertz.

  Singlemode fiber shrinks the core down so small that the light can only travel in one ray. This increases the bandwidth to almost infinity - but it's practically limited to about 100,000 gigahertz - that's still a lot!

   

  Optic Fiber Cable Construction

  

   

  Optical fiber consists of a core and a cladding layer, selected for total internal reflection due to the difference in the refractive index between the two. In practical fibers, the cladding is usually coated with a layer of acrylate polymer or polyimide. This coating protects the fiber from damage but does not contribute to its optical waveguide properties.

  Individual coated fibers (or fibers formed into ribbons or bundles) then have a tough resin buffer layer and/or core tube(s) extruded around them to form the cable core. Several layers of protective sheathing, depending on the application, are added to form the cable.

  Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications.

  A “dopant” is added to the core to actually make it less pure than the cladding. This changes the way the core transmits light. Because the cladding has different light properties than the core, it tends to keep the light within the core. Because of these properties, fiber optic cable can be bent around corners and can be extended over distances of up to 100 miles.
  
  A typical laser transmitter can be pulsed billions of times per second. In addition, a single strand of glass can carry light in a number of wavelengths (colors), meaning that the data-carrying capacity of fiber optic cable is potentially thousands of times greater than copper cable.

   

  Types Of Fiber Optic Cable

  • Plastic cable, which works only over a few meters, is inexpensive and works with inexpensive components.
  • Plastic-coated silica cable offers better performance than plastic cable at a little more cost.
  • Single-index monomode fiber cable is used to span extremely long distances. The core is small and provides high bandwidth at long distances. Lasers are used to generate the light signal for single-mode cable. This cable is the most expensive and hardest to handle, but it has the highest bandwidths and distance ratings.
  • Step-Index multimode cable has a relatively large diameter core with high dispersion characteristics. The cable is designed for the LAN environment and light is typically generated with a LED (light-emitting diode).
  • Graded-index multimode cable has multiple layers of glass that contain dispersions enough to provide increases in cable distances.

  Cable specifications list the core and cladding diameters as fractional numbers. For example, the minimum recommended cable type for FDDI (Fiber Distributed Data Interface) is 62.5/125 micron multimode fiber optic cable.That means the core is 62.5 microns and the core with surrounding cladding is a total of 125 microns.

  • The core specifications for step-index and graded-index multimode cables range from 50 to 1,000 microns.
  • The cladding diameter for step mode cables ranges from 125 to 1,050 microns.
  • The core diameter for single-mode step cable is 4 to 10 microns, and the cladding diameter is from 75 to 125 microns.

  

   

  Indoor Vs. Outdoor Optic Fiber Cable Applications

  For  indoor applications, the jacketed fiber is generally enclosed, with a bundle of flexible fibrous polymer strength members like aramid (e.g. Twaron or Kevlar), in a lightweight plastic cover to form a simple cable. Each end of the cable may be terminated with a specialized optical fiber connector to allow it to be easily connected and disconnected from transmitting and receiving equipment.

  For outdoor applications or use in more strenuous environments, a much more robust cable construction is required. In loose-tube construction the fiber is laid helically into semi-rigid tubes, allowing the cable to stretch without stretching the fiber itself. This protects the fiber from tension during laying and due to temperature changes. Loose-tube fiber may be "dry block" or gel-filled. Dry block offers less protection to the fibers than gel-filled, but costs considerably less. Instead of a loose tube, the fiber may be embedded in a heavy polymer jacket, commonly called "tight buffer" construction. Tight buffer cables are offered for a variety of applications, but the two most common are "Breakout" and "Distribution".

  Breakout Cables normally contain a ripcord, two non-conductive dielectric strengthening members (normally a glass rod epoxy), an aramid yarn, and 3 mm buffer tubing with an additional layer of Kevlar surrounding each fiber. The ripcord is a parallel cord of strong yarn that is situated under the jacket(s) of the cable for jacket removal. Distribution Cables  have an overall Kevlar wrapping, a ripcord, and a 900 micrometer buffer coating surrounding each fiber. These fiber units are commonly bundled with additional steel strength members, again with a helical twist to allow for stretching.

  A critical concern in outdoor cabling is to protect the fiber from contamination by water. This is accomplished by use of solid barriers such as copper tubes, and water-repellent jelly or water-absorbing powder surrounding the fiber.

  Finally, the cable may be armored to protect it from environmental hazards, such as construction work or gnawing animals. Undersea cables are more heavily armored in their near-shore portions to protect them from boat anchors, fishing gear, and even sharks, which may be attracted to the electrical power that is carried to power amplifiers or repeaters in the cable.

  Modern cables come in a wide variety of sheathings and armor, designed for applications such as direct burial in trenches, dual use as power lines, installation in conduit, lashing to aerial telephone poles, submarine installation, and insertion in paved streets.

  To purchase your fiber cables, please click link below:

  Fiber Patch Cables

   

   

   

   

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• Compact Optical Splitter Module for PON Architecture FTTH Deployment

  Feb 8, 2016 by Articles / 627 Views

   

  Passive Optical Network (PON) system has expanded extensively as an optical network in the construction of Fiber To The Home (FTTH) economically. To allow multiple users to share an optical fiber in a PON, the Optical Splitter that branches an optical signal is indispensable. Recently, plug-and-play structures that make use of modules and connectors are desired to simplify the installation construction of optical splitters. Moreover, because the splitter module is installed in the outside plant, high reliability that can endure harsh environmental conditions is a critical requirement. In addition, compactness and cost savings are also important considerations. Therefore, we have developed it by economically using a superior flame-retardant plasticresin for the module case. We have confirmed that the optical splitter modules have excellent optical characteristics and sufficient reliability.

  
  

  1. Introduction of Optical Splitter Modules

  PON system has expanded extensively as an optical network in the construction of FTTH economically. As shown in Fig. 1, PON architecture allows a signal transmitted over a single optical fiber from the telephone exchange office to be shared with multiple users, hence achieving cost reduction per subscriber. Planar Lightwave Circuit (PLC) splitter, an optical splitter is a key to realize the branching of optical signal in the telecommunication network, and currently has a maximum of 32 split ratio capability.

  

  Installation of optical splitter is simplified with the application of latch-on or snap method that can expedite the process with quick plug-in action. This plug-and-play method is commonly applied at the interconnection points in the FTTH network (This method enables field installation of optical components without any special tools or skills in managing bare optical fibers). To effectively deploy with such simple techniques and modular designs, connectorized components are essential to be integrated in the structure design of optical splitters. In addition, flexibility of network is achieved with the application of module terminated with connector cord, which allows easy reconfiguration of the network. Furthermore, in the FTTH PON architecture, the function of Fiber Distribution Hub (FDH) is to house optical splitter outdoor, therefore the FDH is critical in ensuring high reliability against environmental factors. Due to the space constraint in the FDH, down-sizing of optical splitter module design is done. The pervasive FTTH deployment worldwide has been called for an imminent need to develop low-cost solutions. The newly developed small sized and lightweight optical splitter is made from retardant plastic resin with sturdiness comparable to the conventional metal packaging in withstanding outdoor environmental conditions, but at a fraction of its original cost. This article illustrates the development of 1×16, 1×32 and 2×32 Wavelength Division Multiplexing (WDM) optical splitter module. The characteristics and reliability evaluation will also be discussed in this article.

  2. Structure of Optical Splitter Modules

  2.1. PLC-Type Splitter

  As shown in Fig. 2, the optical fiber is being branched to 32 outputs through a 1×32 PLC-type optical splitter. PLC chip is a silica glass embedded with optical wave circuit. The circuit pattern is designed to branch a single input into multiple output channels. Optical fiber is adhered to PLC chip with resin curedby ultraviolet exposure; this interface conforms to Telcordia GR-1209 and GR-1221 test conditions, hence good reliability is ensured. Furthermore, inorder to actualize the size reduction, bend insensitive Single Mode Fiber (SMF) has been introduced into this module.

  

  2.2. Flame Retardant Plastic Package

  The structure of optical splitter module developed is shown in Fig. 3. Bend insensitive fiber with bending radius of 15 mm is applied to the optical splitter module to achieve a considerable size reduction of the packed module. The overall dimension of L118mm×D87 mm×H13 mm is 3/5 of the size of the conventional optical module utilizing SMF of bending radius 30 mm. In addition, as a flame retardant plastic resin has replaced metallic materialin the splitter packaging, the weight decreases to 1/3 of the conventional metallic packaging version.

  

  Figure 4 illustrates the internal configuration of the optical splitter module. The splitter module is terminated with optical connector pigtails. The 2 mm fiber cords are fixed onto the cable retainer with adhesive.This structure is designed to withstand tensile strength of maximum 68.6 N. Moreover, as the optical cord has a similar structure to the loose tube cables, allowing the optical fiber free movement within the cord effects the expansion and contraction of the optical cord that will not exert any external tension onto the fiber.

  

  The structure of strain relief boot is shown in Fig.5. The boot is designed to control the bending radius to a minimum of optical fiber limit, i.e., 15 mm. This prevents an increase in attenuation brought upon by fiber bend. The flexible boot developed has taken factors like hardness, thickness and the quantity of cord per boot into the design considerations to control the bending radius to a minimum of 15 mm when a loadis applied at 90° bend to the optical cord perpendicularly.

  

  3. OPTICAL PERFORMANCE AND CHARACTERISTIC

  3.1. Functionality of FDH

  Figure 6 captures the appearance of FDH system in configuration with optical splitter module load. The hub, optical connector, and optical adapters are all mounted onto a panel to enable ease of operation with a latch mechanism. The pigtail is elegantly managed in a U-shape through the mandrel. This plug-and-play method makes installation extremely simple and efficient.

  

  3.2. Fundamental Optical Characteristics

  The 1×16 and 1×32 splitter modules were fabricated to be mountable onto the above described fiber distribution hub. The vacant port (a port which is not in service) present in the FDH will result in back reflections of the optical signal. To prevent return loss from the end face of vacant port, SC connector is polished to an Angled Physical Contact (APC) interface. Data below tabulates the optical characteristics of the optical splitter module, inclusive of the connector pigtails.

  The histograms shown in Figs. 7 and 8 illustratethe insertion loss performance of 1×16 and 1×32 optical splitter module respectively. At operating wavelength 1310 nm, the average insertion loss of 1×16 splitter stands at 13.23 dB while that of 1×32 splitter is 16.33 dB. Similarly, at 1550 nm operation wavelength, the insertion loss of 1×16 and 1×32 splitter module is 13.10 dB and 16.22 dB respectively. In addition, the standard deviation of 1×16 splitter is 0.29 dB while 1×32 splitter yields a standard deviation of 0.34dB. At the same time, this value decreases to 0.23 dB for 1×16 splitter and 0.28 dB for the 1×32 splitter at wavelength 1550 nm.

  

  The performances of other optical characteristics apart from insertion loss are shown in Table 1. These results show consistent good performances, as exhibited in the insertion loss histogram, in characteristics including uniformity, return loss and PDL values.

  

  3.3. Temperature dependent loss

  History from past experimental results has shown that components terminated with optical pigtail cord are susceptible to insertion loss fluctuation with temperature change. To isolate the effects of cordage expansion/contraction on the optical fiber within, the optical cord is designed to allow free movement of optical fiber, thus eliminating the external stress fromthe expansion/contraction of the cord. Figure 9 depicts the insertion loss variation of the 1×32 optical splitter module during temperature cycling from −40 °C to +85 °C. The average, minimum, and maximum values obtained from the 32 output ports are illustrated in the graph shown in Fig. 9. From the graph, the maximum loss deviation between the ports with maximum and minimum insertion loss is 0.17 dB. This result has an evident exceptional stability of the optical splitter module that is developed.

  

  3.4. Wavelength dependent loss

  The wavelength dependent loss of the 1×32 optical splitter module is shown in Fig. 10. The performances of insertion losses over wavelengths from 1260 nm to 1680 nm are measured. Again, the average loss from 32 ports and minimum and maximum wavelength dependent losses are illustrated in the graph. The average deviation is 0.36 dB while the maximum deviation from all the 32 ports is 0.86 dB.

  

  This proves that the splitter module has shown resilience in insertion loss variation over a broad spectrum of wavelength.

  A variety of optical devices are stored in this optical splitter module, making it multifunctional. An example is the 2×32 WDM optical splitter module shown in Fig. 11 and the structure of its cable retainer in Fig.12. A WDM filter was built in front of a 1×32 splitter module, enabling the structure to have multiple wavelengths.

  

  Figure 13 shows the wavelength dependent loss of the 2×32 WDM optical splitter module. With the WDM filter, the wavelength ranging from 1530nm to1570nm are transmitted from the B port, and the other wavelength ranges are transmitted from the A port. The wavelength dependent loss of A port and B port are split evenly among the 32 fibers, hence excellent loss performance is obtained in each port.

  

  4. Reliability of Optical Splitter Modules

  The reliability of 1×32 splitter module is evaluated in accordance to test procedures stipulated in the Telcordia GR-1209 and GR-1221. The test conditions and the results of the 1×32 splitter module measured at 1550 nm are shown in Table 2. The average, maximum, and minimum values of 32 output ports measured are recorded in Table 2. The results of side pulltest and cable retention test are maximum in-situ datamonitored during load application onto the cable cord. On the other hand, the recorded data of damp heat, temperature cycling, mechanical shock, vibration, and water immersion shows the variation of insertion loss before and after the test conditions. From the results, it is confirmed about the reliability of 1×32 splitter module.

  

  The results of high temperature and humidity test are depicted in Fig. 14. The optical splitter samples underwent a total of 2000 hours of storage at 85 °C and of 85% relative humidity. Insertion loss data at 100 hrs, 168 hrs, 500 hrs, 1000 hrs, and 2000 hrs juncture were measured. The average insertion loss of the 32 ports, maximum and minimum insertion loss measured at 1550 nm are displayed in the graph. From the graph in Fig. 14, it is concluded that there is very minimal loss variation even after 2000 hrs. The optical splitter module has shown good stability when exposed to high temperature and humidity conditions.

  

  Furthermore, to meet the flame retardant requirements for optical components and accessories, we have applied frame retardant plastic material of 1.5 mm thickness complying to UL-94 V-0. On the same note, the jacket of optical fiber cord is made of grade V-0 flame retardant PVC.

  5. Conclusion

  A compact and economical optical splitter that boasts of superior optical performance and reliability against stringent environmental conditions suited for outdoor installation has been successfully developed. This plug-and-play design for installation of the above optical splitter has enabled simple and speedy installation, at the same time provided added flexibility for future network reconfigurations, thus making this optical splitter module the perfect solution for PON architecture FTTH deployment.

   

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