Monthly Archives: October 2014

Purchase Fibre Adapter Panels

Because the laser light is dangerous, and the ends of every fibre optic cable (have a small core) must be encased in some kind of enclosure. So, the fibre enclosure not only protects humans from laser light but also protects the fibre from damage. Fibre wall plates and fibre patch panels are two main types of fibre optic enclosures.

As previously mentioned, fibre optic cables have a very small core that can be easily damaged if not protected properly. Also, to be consistent with the minimum size of a fibre optic loop and not violate the critical angle, we need to have a way to keep excess fibre optic patch cables, as well as terminated building fibre, neat and protected from damage. Fibre optic wall plates and patch panels allow the cable installer to protect the delicate fibre cable from damage, while still making it usable for the network administrator.

Overview of Fibre Enclosure

A common device that is used as a fibre optic cable enclosure is called a Lightguide Interconnection Unit(LIU), as showed in Figure 1. The LIU provides a location to terminate individual fibre optic strands into a patch panel, which will be discussed in the next article. A LIU is generally made of galvanized steel that is then powder-coated to provide durability. Most major LIU manufacturers make their devices 19 inches wide so they can be installed in a normal communications rack, If the LIU is to be located in an environment where there is a risk of moisture or corrosives, the LIU can be sealed with gaskets to make it virtually waterproof. Most LIUs have swing out trays in the front and the back to provide easy access to the patch panel to ensure that all loops are a minimum diameter, so the cable will not get damaged and maximum light can traverse the cable.

LIU500x500

Figure 1. Lightguide Interconnection Unit(LIU)

What Is Fibre Adapter Panel (FAP) and How to Use It?

Patch panels for fibre optic cables also called fibre patch panels, which are usually installed into the LIU. Because the core and cladding of two fibre optic cables that are to be joined together must match perfectly, the fibre patch panel must be manufactured to exact specifications and some standard type connector must be used to ensure a good fit. (fibre option connectors are discussed in the next section.) Another fibre patch panel issue deals with attenuation. Remember from the previous article discussed that when you splice or join a fibre optic cable, you can introduce additional light loss or attenuation. The same holds true for the fibre optic patch panel. The connectors on the patch panel should identify the total loss at various wavelengths, and these losses should be added to any other cable loss on that particular cable to ensure compliance with the standard and good operation of the fibre optic cable. Figure 2 is an LC adapter panel.

lc fiber adapter panel

Figure 2. LC fibre adapter panel

Fibre Adapter Panel (FAP) is used for patching a fibre cable to the enclosures like fibre wall cabinets, rack mounts fibre cabinets or rack mount fibre shelf. It allows you to make quick and easy fibre patch panel connections as they can snap into the fibre optic enclosures easily. Fibre adapter panel is designed to fit fibre optic blank patch panel, rack and wall mount enclosure. To purchase this kind of fibre adapter panel, please visit www.fs.com.

The Conventional Fibre Adapter Plates Need to Improve

Optical fibre has been used as a medium for telecommunication as well as networking because it’s flexible enough and could be bundled as cables. Optical fibre has been especially advantageous for long-distance communications because light propagates through the fibre with little attenuation compared to electrical signals carried by conventional wire cables. Over short distances, for instance networking within a building, optical fibre interconnect cables save space in cable ducts because a single fibre can carry more data than a single electrical cable.

Interconnect cables are generally used as intra-equipment jumpers or patch cords. For example, some typical applications include patching active electronics to nearby patch panels, cable cross-connection on distribution frames, and connecting work area outlets to terminal equipment. Fibre optic patch cords comprise a length of cable with a plug or connector on one, or both ends, and can also be referred to as connectorized fibre optic cables. A patch panel typically comprises a connecting hardware system (e.g., racks, adapter plates, arrays of adapters, etc.) that facilitates cable termination and cabling administration via the use and administration of standard-conforming adapters. (The following figure is a 12 port fibre patch panel)

12 port fiber patch panel

Various fibre optic cable connector and adapter designs can be used to meet the requirements of corresponding Fibre Optic Connector Intermateability Standard (FOCIS) documents. Note that the term adapter, when used in reference with optical fibre, has been defined by the optical fibre industry and standards organizations as a mechanical termination device designed to align and join two like optical connectors.

In some designs, fibre adapter plates provide the means to support and align the interconnection of connectorized fibre optic cables in structured voice or data cabling networks. Conventionally, fibre adapter plates use a metal or plastic plate or support panel having a number of cutouts to accept discrete fibre optic adapters which are typically linked to the adapter plate by screws or clips. Therefore, these adapter plates use a removable attaching mechanism (e.g., screws, clips, latches, etc.) to attach the adapter plate to an enclosure or patch panel.

However, such conventional adapter plates suffer from drawbacks due to the assembly of so many discrete parts. For example, alignment of the connecting optical fibres is crucial to minimize loss across the adapter. While internal fibre optical interface details (e.g., alignment, cable separation, etc.) are specified by rigid standards, the adapter to adapter plate connection is more springy. As a result, excessive tolerances can result in additional mechanical play between the adapter and the adapter plate which can, sometimes, to enable excessive stresses and bend radii of the connecting fibre optic cables.

As a further example, such conventional assemblies by their nature require costly assembly steps. As a cost saving measure, some of the assembly steps can be passed on to the end user. However, this can lead to increasing set up time, having costs of its own, and can result in end user frustration. Furthermore, conventional adapter plate panels are often unlabeled or stamped with labels that are hard for the end user to ascertain, specially when the adapter plate is fully outfitted with adapters and cabling.

It is thus desired to provide fibre adapter plates that improve upon these and other deficiencies of conventional fibre adapter plates.

Fibre adapter panels provided By FS, loaded with LC, SC, ST, FC, MT-RJ, MPO and unloaded blanks. With products compatible for trusted brands including Black Box, Wirewerks, Mr-technologies, Corning, Leviton, Panduit Opticom adapter panel and more.

PON Splitters And Passive Optical Network

Passive Optical Network (PON), comprises a family of Physical Layer (Layer 1) access technologies based on the specifications developed by the Full-Service Access Network(FSAN) initiative for an ATM-based Passive Optical Network scheme produced by an international consortium of vendors and ratified by the ITU-T within the G.983.1 standard (October 1998). A PON is a fibre-optic local loop network without active electronics, such as repeaters, which can be both costly and troublesome. Rather, a PON uses inexpensive passive optical splitter and fibre coupler to deliver signals form the network edge to multiple customer premises. The PON splitters are placed at each fibre junction, or connection, throughout the network, providing a tremendous fan-out of fibre to a large number of end points. By eliminating the reliance on expensive active network elements and the ongoing powering and maintenance expenses associated with them, carriers can realize significant cost savings. PON technology usually used in the local loop to connect customer premises to an all-fibre network.

In fact, an efficient and reliable optical network (PON), depends on appropriate testing and measurement. During the construction phase, proper testing is the only way to guarantee that all the required transmission specifications are met, the network is ready for actual traffic, and subscribers are supplied with the expected service quality. During initial commissioning and subscriber activation, testing and diagnosis can ensure that the whole system operates within the acceptable specifications. When the network is activated and operation begins, the quality of service (QoS) must be tested and monitored to meet up with service-level agreements with subscribers. When problems are detected and diagnosed (e.g. Low signal or no signal), troubleshooting networks help to minimize network downtime, rapidly restore failed services, and efficiently manage network performance.

passive optical network

Figure 1 The architecture of a passive optical-access network

A PON is a point-to-multipoint, fibre-to-the-premises network architecture in which unpowered optical splitters (either splitting in optical power or wavelength) are used to enable a single optical fibre to serve multiple premises. Figure 1 shows the generic PON architecture. A PON does not use any active electronic components (devices consuming power), form the central office (CO) to the consumers’ premises. The network carries a single strand of fibre, which undergoes multiple splits to serve many consumer installations. This splitting is achieved by way of passive splitters. To the side of the local exchange there is an optical line termination (OLT), on the user side there is an optical network optical fibres and one or more splitters (in cascade), a number of ONUs are connected to an OLT in a tree topology. An ONU can be combined with a network termination unit(NT). This produces an optical network termination (ONT). The OLT has the interfaces with the backbone network that supply the services to the users. Hence a PON’s passive part consists of splitters and fibres located within the field. Reasonably complex active components are needed in the local exchange (the OLT) and on the side of users (the ONU/ONTs).

Unlike the point-to-point terrestrial and undersea amplified wavelength-division-nultiplexed (optical amplifier) fibre systems, the point-to-multipoint nature of PON has made the optical diagnosis, performance monitoring, and characterization a challenge. The key tests performed during a PON’s construction include total link loss measurement (optical power budget), optical return loss (ORL) measurement–especially when cable TV (CATV) services are provided, link characterization using an optical time-domain reflectometer (OTDR). During a PON’s opteration, network operators need to detect signal presence, measure them,and verify that they are within acceptable power ranges. Thorough performance assessment, accurate bit-error-rate (BER) measurement can help to define competitive, customer-retaining service-level agreements, and, most importantly, to make sure and sustain them.

Low-cost Optical Amplifiers

Communications can be broadly defined as the transfer of information from one point to another. In optical fibre communications, this transfer is achieved by using light as the information carrier. There has become an exponential growth in the deployment and capacity of optical fibre communication technologies and networks over the past twenty-five years.

Optical technology is the dominant carrier of global information. It is also central to the realisation of future networks that will have the capabilities demanded by society. These capabilities include virtually unlimited bandwidth to carry communication services of almost any kind, and full transparency that allows terminal upgrades in capacity and flexible routing of channels. Many of the advances in optical networks have been completed by the advent of the optical amplifier.

In general, optical amplifiers can be divided into two classes: optical fibre amplifiers and semiconductor amplifiers. The former has tended to dominate conventional system applications such as in-line amplification used to compensate for fibre losses. However, due to developments in optical semiconductor fabrication techniques and device design, especially over the last five years, the semiconductor optical amplifier (SOA) is showing great promise for use in evolving optical communication networks. It can be utilised as a typical gain unit but also has many functional applications including an optical switch, modulator and wavelength converter. These functions, where there is no conversion of optical signals into the electrical domain, are required in transparent optical networks.

Low-cost Optical Amplifiers

Cost reduction of optical amplifiers is of increasing concern because of continual pressure on the pricing of optical networking equipment, because of changes in applications and network architectures which are extending the range of applications of amplifiers beyond the line amplifier repeaters of the core network, and because the dominant EDFA technology is not as easily amenable to cost reduction through integration as other technologies such as semiconductors.

Low-cost optical amplifiers will be used in the highest volume, most cost sensitive applications, such as metro and access network line amplifiers, single-channel amplification for high speed, advanced modulation format channels, cable television distribution booster amplifiers(CATV) , and ASE sources for WDM passive optical networks (PONs). The complementary technologies for low-cost amplifiers, such as semiconductor optical amplifiers, and erbium-doped waveguide amplifiers (EDFA), (EDWAs) are covered. EDFAs, which is the dominant technology, comprises multiple components with different features and is based on different technologies.

The challenges and opportunities for reducing the costs of the primary components of EDFAs and the labor costs of assembling EDFAs are discussed, EDWAs offer opportunities for cost reduction by integrating the features of many of the components required for optical amplifiers. However, the lower efficiency of converting pump-to-signal power in erbium-doped planar waveguides compared with erbium-doped fibre, poses an obstacle to the commercial realization of the potential cost advantages of EDWAs, A recent approach is the PLC erbium-doped fibre amplifier, in which many of the passive devices are integrated on a PLC but the gain is provided by an erbium-doped fibre. This approach combines the advantages of PLC integration with the performance and pump efficiency of erbium-doped fibre and is especially advantageous for complex amplifier architectures requiring various optical components.

FS DWDM optical amplifier modules provide multi-function, low noise, Erbium-Doped Fibre Amplifier (EDFA) solutions that are ideal for metro Dense Wavelength Division Multiplexing (DWDM) applications. This family of C-Band 40 channels optical amplifiers is part of the fibre driver optical multi-service platform solution.

About Multimode Fibre

Multimode fibre is a kind of optical fibre mostly used in communication over short distances, for example, inside a building or for the campus. Typical multimode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters (2000 feet) – greater than sufficient for almost all premises applications.

Multimode fibre optic cable has a large diametral core which allows multiple modes of light to propagate. For this reason, large number of light reflections created because the light goes through the core increases, creating the ability for more data passing at a given time. Due to the high dispersion and attenuation rate using this type of fibre, the number of the signal is reduced over long distances. This application is commonly used in short distance, data and audio/video applications in LANs. Broadband RF signals, such as what fibre optic companies commonly use, can’t be transmitted over multimode fibre.

Multimode fibre is generally 50/125 and 62.5/125 in construction. It means that the core to cladding diameter ratio is 50 microns to 125 microns and 62.5 microns to 125 microns.

50-125

Multimode fibres are recognized by the OM (“optical mode”) designation as outlined in the ISO/IEC 11801 standard.

  • OM1 Fibre, for fibre with 200/500 MHz*km overfilled launch (OFL) bandwidth at 850/1300nm (typically 62.5/125um fibre)
  • OM2 Fibre, for fibrewith 500/500 MHz*km OFL bandwidth at 850/1300nm (typically 50/125um fibre)
  • OM3 Fibre, for laser-optimized 50um fibre having 2000 MHz*km effective modal bandwidth (EMB, often known as laser bandwidth), created for 10 Gb/s transmission.
  • OM4 Fibre, for laser-optimized 50um fibre having 4700 MHz*km EMB bandwidth made for 10 Gb/s, 40 Gb/s, and 100 Gb/s transmission.

Multimode Fibre Types

The transition between the core and cladding can be sharp, which is named a Step-index multimode Fibre, or a gradual transition, which is named a Graded-Index multimode Fibre.

Step-Index Multimode Fibre – Because of its large core, a few of the light rays that constitute the digital pulse may travel a direct route, whereas others zigzag as they bounce off the cladding. These alternate paths result in the different groups of light rays, identified as modes, to reach separately at the receiving point. The pulse, an aggregate of different modes, starts to disseminate, losing its well-defined shape. The necessity to leave spacing between pulses to avoid overlapping limits the quantity of information which can be sent. This kind of fibre is most effective for transmission over short distances.

Graded-Index Multimode Fibre – Includes a core in that the refractive index diminishes gradually from the centre axis out toward the cladding. The higher refractive index in the centre makes the light rays moving down the axis advance more slowly than these near the cladding. Because of the graded index, light in the core curves helically rather than zigzag off the cladding, reducing its travel distance. The shortened path and the greater speed allow light at the periphery to reach a receiver at about the same time as the slow but straight rays in the core axis. The end result: digital pulse suffers less dispersion. This kind of fibre optic cable is most effective for local-area networks.

Applications

The device used for communications over multi-mode optical fibre is cheaper than that for single-mode optical fibre.Typical transmission speed and distance limits are 100 Mbit/s for distances up to 2km (100BASE-FX), 1 Gbit/s up to 1000m, and 10 Gbit/s up to 550m.

Due to its high capacity and reliability, multi-mode optical fibre usually used for backbone applications in buildings. A large number of users consider the advantages of fibre nearer to the user by running fibre to the desktop or to the zone. Standards-compliant architectures such as centralized cabling and fibre to the telecom enclosure offer users the opportunity to leverage the distance capabilities of fibre by centralizing electronics in telecommunications rooms, instead of having active electronics on each floor.