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How Great Of Fiber Optic Cables

Fiber optic cables are used frequently for today’s telecommunication network because of their high bandwidth, high reliability and relatively low cost. For a layman, fiber optical cable or FOCs as they are often called, is a plastic or glass fiber which permits the transmission of communications over large distances and at higher rates. They present wire almost superfluous, because they pass the same, but there are a lot of loss. These cables are unique because they are not affected by electromagnetic interference. Use these cables in performing image used in the fiber.

Each cable can not beyond the permissible limit. Fiber optic cable is very safe and more reliable than the traditional copper wire. Most of these cable to work in high-pressure environments. A fiber optic cable assembly includes a tube, a track and fasteners in addition to the conventional fiber bundles.

The cable tubes have both front and rear surfaces to it. These cables operate with the help of photons. These photos are transmitted to a second quantum dot which is placed between mirrors. These mirrors absorb the photons and bounce them back to the quantum dot until it absorbs it.

The fiber optic cables are used for carrying different services pertaining to data, voice, cable TV, and video. The fiber optic cables keeps the electronic equipments far away from environment that are subjected to high temperature, stem, dust, smoke and so on. The unique feature of these fiber optic cable is that stainless steel lens and fiber cables can be easily replaced without any further calibration.

For the installation of fiber optic cables, fiber optic cable blowers are designed. The unique feature of these fiber optic is that they carry information in the form of light. These cables are very useful in transporting both audio and video signals over short and long distances. If a fiber optic cable is broken, another cable has to be fitted in between the connectors rather than soldering or twisting them. Fiber optic technologies have found its place in many applications. They are widely used in telecommunications, CCTV security places, and local area networks and so on.

Glass fibers are made use of for fiber optic cabling. They hardly provide any change in the signals they carry over long distances. Engineers found that by adding some additional chemicals into the existing silica, they can change the properties of the glass used for the cable (glass fiber cable). Althouth, both glass and plastic can be used in the manufacture of cable, glass is the preferred one used in the manufacture of cable, used for long distance transmission communication. The purpose of glasses in total internal reflection transmission.

A fiber optic cable consists of a core which is made of glass silica. Through this core, the light is guided. The core is covered with a material whose refractive index is slightly lower than that of the core. Two optical fibers are connected via mechanical splicing or fusion splicing. This process involves lots of skills as microscopic precision is required to align them.

Regardless of the application used in optical fiber, they will stay here. Their unique features and capabilities, to ensure that they will continue to spread widely used in communications industry for many years.

What Is an Optical Attenuator?

LC Plug Type Fixed Attenuator An optical attenuator decreases the strength of an optical signal passing through it to a fiber optic cable or open air. The intensity of the signal is described in decibels over a specific distance the signal travels. It is the strength, or amplitude of the signal that changes and not the overall waveform or frequency, so the optical signal remains undistorted for use in the desired application. Optical attenuators are often used in optical communication systems, in which the attenuation, also called transmission loss, helps with the long-distance transmission of digital signals. The most common optical attenuator types include fixed and continuously variable attenuators.

Often installed where signals are transmitted from, an optical attenuator can apply the principle of gap loss so the signal intensity is lowered to the optimal level over a given distance. Attenuators installed elsewhere along the optical fiber will not lower the signal strength enough, but some devices utilize signal absorbing or reflecting components to compensate. An optical fiber connector is often attached to the optical attenuator which typically has an adapter with a female configuration. The attenuator itself usually has a cylindrical or even box-like structural shape which determines the type of equipment in which it can be installed.

The fixed variety of optical attenuator, sometimes found in an electronic circuit, does not reflect light signals to reduce their intensity. It is generally used where the transmission of data needs to be highly accurate. The device’s function is determined by the amount of power it can handle in addition to important variables such as performance versus temperature and frequency range. Most optical attenuators utilize resistors, but a variable optical attenuator uses metal semiconductor field effect transistors or other solid state components. Attenuation intensity is adjustable so the signals in a fiber optic communication system can be changed to accommodate fluctuating power levels, protecting the system from damage.

A variable optical attenuator can be mounted on a printed circuit board, or used in test devices such as an optical power meter. Many attenuators are installed in-line with an optical fiber cable in order to adjust the transmitted signal accordingly. They are sold by many retailers and manufacturers online so one can assess their characteristics by reading the product specifications. Aspects to consider include the average and peak power the device can tolerate, how much attenuation it provides, as well as its overall dimensions and the type of environment it can operate in.

SC fiber optic connector basic structure

More than a dozen types of fiber optic connectors have been developed by various manufacturers since 1980s. Although the mechanical design varies a lot among different connector types, the most common elements in a fiber connector can be summarized in the following picture. The example shown is a SC connector which was developed by NTT (Nippon Telegraph and Telephone) of Japan.

A SC Connector Sample

SC Connector Structure

Elements in a SC connector

1. The fiber ferrule.

SC Connector Fiber Ferrule

SC connector is built around a long cylindrical 2.5mm diameter ferrule, made of ceramic (zirconia) or metal (stainless alloy). A 124~127um diameter high precision hole is drilled in the center of the ferrule, where stripped bare fiber is inserted through and usually bonded by epoxy or adhesive. The end of the fiber is at the end of the ferrule, where it typically is polished smooth.

2. The connector sub-assembly body.

The ferrule is then assembled in the SC sub-assembly body which has mechanisms to hold the cable and fiber in place. The end of the ferrule protrudes out of the sub-assembly body to mate with another SC connector inside a mating sleeve (also called adapter or coupler).

3. The connector housing

Connector sub-assembly body is then assembled together with the connector housing. Connector housing provides the mechanism for snapping into a mating sleeve (adapter) and hold the connector in place.

4. The fiber cable

Fiber cable and strength member (aramid yarn or Kevlar) are crimped onto the connector sub-assembly body with a crimp eyelet. This provides the strength for mechanical handing of the connector without putting stress on the fiber itself.

5. The stress relief boot.

Stress relief boot covers the joint between connector body and fiber cable and protects fiber cable from mechanical damage. Stress relief boot designs are different for 900um tight buffered fiber and 1.6mm~3mm fiber cable.

How are Optic Fiber Made?

Many People ask how fiber optics are made. You can’t just use “regular” glass. If you were to make optical fiber from ordinary window glass, the light that you shine through it would have a difficult time traveling more than a few kilometers, let alone the distances necessary for long distance transmission. That’s because ordinary glass contains distortions, discolorations and other impurities that would quickly absorb, reflect, or otherwise disperse light long before it could travel any great distance.

In contrast, because optical fiber is actually made from very pure glass, the light traverses great distances largely unimpeded by impurities and distortions.

Fiber Optic Cable – Light How it Works

To transmit light effectively, fiber optic cable must contain glass of the highest purity. The process of making glass with this level of purity is very demanding, requiring careful control over the materials and processes involved. Yet, the fundamental concept is simple. Essentially, optical fiber is made from drawing molten fiber from a heated glass blank or “preform.” The following provides a more detailed explanation of the three basic steps involved in making optical fiber.

Step #1

Create the Fiber Optic Preform

A preform is a cylindrical glass blank that provides the source material from which the glass fiber will be drawn in a single, continuous strand.

Making a preform involves a chemical process known as Modified Chemical Vapor Deposition (MCVD). This process involves bubbling oxygen through various chemical solutions including germanium chloride (GeC14) and silicon chloride (SiC14).

The bubbling chemicals produce gas that is directed into a hollow, rotating tube made of synthetic silica or quartz. A torch is moved up and down the rotating tube, resulting in very high temperatures that cause the gas to react with oxygen to form silicon dioxide (Si02) and germanium dioxide (Ge02). These two chemicals adhere to the inside of the rotating tube where they fuse together to form extremely pure glass.

Creating the preform takes several hours, after which additional time is required for the glass blank to cool. Once cooled, the glass is tested to ensure that it meets quality standards, especially in terms of index of refraction.

Step #2

Draw Optical Fiber from the Preform

In this step, the finished glass preform is installed at the top of a tower which supports various devices used in the fiber drawing process.

The process begins by lowering one end of the preform into an in-line furnace that produces heat in a range of 3,400 to 4,000 degrees Fahrenheit. As the lower end of the preform begins to melt, it forms a molten glob that is pulled downward by gravity. Trailing behind the glob is a thin strand of glass that cools and solidifies quickly.

The equipment operator threads this glass strand through the remainder of the devices on the tower, which include a number of buffer coating applicators and ultraviolet curing ovens. Finally, the operator connects the fiber to a tractor mechanism.

The tractor device pulls the glass strand from the preform at a rate of 33 to 66 feet per second. The actual speed at which the tractor pulls the strand is dependent upon the feedback information the device receives from a laser micrometer that continually measures the fiber’s diameter.

At the end of the run, the completed fiber is wound onto a spool.

Step # 3

Test the Fiber Optics

The completed optical fiber must undergo a number of tests to determine the quality of the finished product. The following are a few of the assessments involved:

• Refractive index profile

• Fiber geometry inspection, including core, cladding and coating

• Tensile strength • Bandwidth capacity

• Attenuation at different wavelengths

• Chromatic dispersion

• Operating temperature and humidity range

Quality Control in Optical Fiber Production

Various factors influence the quality and purity of the optical fiber produced. These include: Chemical Composition – Achieving optimal ratios of the various chemicals used to create the preform is important for achieving glass purity. This mixture of chemicals also determines the optical properties of the fiber that will be produced from the preform, including coefficient of expansion, index of refraction, and so forth. Gas Monitoring – It is crucial that the gas composition and rate of flow be monitored throughout the process of creating the preform. It is also important that any valves, tubes and pipes that come into contact with the gas be made of corrosion-resistant materials.

Heat and Rotation – The hollow cylinder that is used to create the preform must be heated at the proper temperature and continually rotated to enable the chemicals to be deposited evenly.

Relationship Between The Optical Coupler And PLC Splitter

In fact, splitter is named for the function of the device, coulper named for its working principle, splitter may be based coupler, and may be based on the waveguide or the separating element, coupler can be done either the splitter, but also can be done WDM, attenuator.

Optical coupler either split optical signals into multiple paths or combines multiple signals on one path. Optical signals are more complex than electrical signals, making optical couplers trickier to design than their electrical counterparts. Like electrical currents, a flow of signal carriers, in this case photons, comprise the optical signal. However, an optical signal does not flow through the receiver to the ground. Rather, at the receiver, a detector absorbs the signal flow. Multiple receivers, connected in a series, would receive no signal past the first receiver which would absorb the entire signal. Thus, multiple parallel optical output ports must divide the signal between the ports, reducing its magnitude. The number of input and output ports, expressed as an N x M configuration, characterizes a coupler. The letter N represents the number of input fibers, and M represents the number of output fibers. Fused couplers can be made in any configuration, but they commonly use multiples of two (2 x 2, 4 x 4, 8 x 8, etc.). optical coupler

PLC Splitter is a device that split the fiber optic light into several parts by a certain ratio. The simplest couplers are PLC Splitters. These devices possess at least three ports but may have more than 32 for more complex devices.PLC Splitters are important passive components used in FTTX networks. But two kinds of fiber splitters are popular used, one is the traditional fused type PLC Splitter (FBT splitter), which features competitive prices; the other is PLC PLC Splitter, which is compact size and suit for density applications. Both of them have its advantages to suit for different requirement.

PLC Spliiter

PLC Splitter typical parameter include input and output part cable length, splitting ratio, working wavelength and with what kind of fiber optic connectors. Just like fiber patch cable, fiber splitters are usually with 0.9mm, 2mm or 3mm cables. 0.9mm outer diameter cable is mostly used in stainless steel tube package PLC Splitters, while 2mm and 3mm cables are mostly used in box type package fiber splitters. Based on working wavelength difference there are single window and dual window PLC Splitters. And there are single mode fiber splitter and multimode fiber splitter. Typical connectors installed on the PLC Splitters are FC or SC type.

Optical coupler or PLC splitters are available in a selection of styles and sizes to separate or combine light with minimal loss. All couplers are produced employing a proprietary procedure that produces reliable, low-cost devices. They’re rugged and impervious to common high operating temperatures. Couplers can be fabricated with custom fiber lengths or with terminations of any type.

Application of optical communication is still broad prospects

Once the Nortel global leader in fiber optic communications during the Internet bubble in 2000, the money in the acquisition of a large number of optical communications research and the production of small and medium enterprises, the industry has been criticized in the subsequent bankruptcy of Nortel. In fact, Nortel grasp of technology trends, the direction is right, unfortunately, Nortel too hasty, global demand for optical communication was not to such an extent.

But now the situation is very different compared with around 2000. The rapid development of mobile Internet and the widespread popularity of smart mobile terminal equipment, being a huge challenge to the global telecommunications network capacity, transmission speed. The era of “data flood peak to optical communication technology has always been known by the transmission bit of new development opportunities and a huge space. Optical communication technology not only did not fall behind, the contrary, the optical communication industry chain, from fiber optic cable system equipment, terminal equipment to optical devices, a critical period in the comprehensive technology upgrade.

The field of optical communication is a noteworthy event, the National Development and Reform Commission recently organizing the preparation of strategic emerging industries key products and services Guidance Catalogue, which in conjunction with the relevant departments, the optical communication technology and product responsibility and selected emerging industries of strategic focus products.

In fiber optics, including FTTx G.657 optical fiber, broadband long-distance high speed large capacity optical fiber transmission with G.656 optical fiber, photonic crystal fiber, rare earth doped fiber (including ytterbium doped fiber, erbium doped fiber and thulium doped fiber, etc.) the laser energy transmission fiber, and has some special properties of new optical fiber, plastic optical fiber, polymer optical fiber is fully finalists. The upgrade of the fiber optic technology, will bring the data transmission capacity, distance, quality leap.

In the field of fiber access equipment, passive optical network (PON), wavelength division multiplexer (WDM),OLT and ONU on the list. Optical transmission equipment, especially the line rate of 40 Gbit/s, 100Gbit/s large capacity (1.6Tb/s and abobe) DWDM equipment, reconfigurable optical bifurcation Multiplexer (ROADM) wavelength division multiplexing system ran cross-connect (OXC) equipment, large-capacity high-speed OTN optical transport network equipment as well as packetized enhanced OTN equipment, PTN packet transport network equipment also impressively. These products are “broadband China” works to promote a powerful weapon; both long-distance backbone network, metropolitan area network or access network even close to the user’s “last mile” of these products will come in handy.

The major products are classified as strategic emerging industries in the field of optical devices, high-speed optical components (active and passive). This is the core and foundation of the field of optical communication technology, device development, the improvement of integration, function enhancement can bring significantly reduce the cost of system equipment and provide a performance boost.

At the same time, the annual OFC / NFOEC (fiber-optic communications exhibition) will be held in late March in California. This event will showcase the latest technology and research progress of the global optical component modules, systems, networks and fiber optic products, represents a new trend of development of optical communication technology.

100G for ultra-high-speed network technology is the current OFC hot one. 2012 100G technology on a global scale backbone network level scale application of 100G optical network applications will rapidly expand with the 100G device further mature. In the same time, the industry has also increased efforts to develop the 100G optical modules, silicon photonics technology pluggable multi-source agreement 100G CFP MSA CPAK optical module has been available. Outside the backbone network, 100G MAN application is the current one of OFC discussion topic.

The rise of cloud computing brings data center construction boom, 100G technology in the data center is a popular data center for high-speed pluggable optical devices is also a hot topic. Experts believe that photonic technology has a key role to play in the large enterprise data centers, but this is only a start, the size of the new cloud computing data center such as a warehouse, with more than 100,000 servers carrying the computing and storage resources, the required network bandwidth than PB level. These data centers only optical communications technology in order to achieve VCSEL (vertical cavity surface emitting lasers) and multi-mode fiber has played an important role, and will continue to introduce new fiber optic communication technology.

Things You Should Know About Filter WDM

Wavelength-division multiplexing (WDM) is overtaking since the leading technology in point-to-point transmission links. One key method is a tunable optical filter. Important features of this type of filter include low insertion loss, narrow bandwidth, high sidelobe suppression, large dynamic range, fast tuning speed, a simple control mechanism, small size, and expense effectiveness. Filter WDM module will depend on Thin Film Filter (TFF) technology. The FWDM is extensively found in EDFA, Raman amplifiers, WDM networks and fiber optics instrumentation. The unit combines or separates light at different wavelengths in the wide wavelength range. Since FWDM series offer minimal insertion loss, low polarization dependence, high isolation and excellent environmental stability, perfect for very fast WDM network systems. It really is traditionally used in optical fiber systems:1310/1550nm, 1480/1550nm, 850/1310nm, 980/1550nm and 1310/1490/1550nm.

FWDM Main Features:

Wide Operating Wavelength Range;
Low Insertion Loss;
Ultra Flat Wide Passband;
High Channel Isolation;
High Stability and reliability;
Epoxy-free on Optical Path.
FWDM Applications:
Testing Instruments;
FTTH Tri-Play System.

WDM is a method of combining multiple signals on lasers at various infared (IR) wavelengths for transmission along fiber optic media. Each laser is modulated by an impartial pair of signals. Wavelength-sensitive filters, the IR analog of visible-light color filters, are employed on the receiving end.

WDM is comparable to frequency-division multiplexing (FDM). But rather than going on at radio frequencies (RF), WDM is done inside the IR element of the electromagnetic (EM) spectrum. Each IR channel carries several RF signals combined by using FDM or time-division multiplexing (TDM). Each multiplexed IR channel is separated, or demultiplexed, in the original signals with the destination.

The usage of WDM can multiply the effective bandwidth of an fiber optic communications system with a large factor. However its cost should be compared to the choice of utilizing multiple fibers bundled in to a cable. A fiber optic repeater device referred to as erbium amplifier plans to make WDM a cost-effective long-term treatment for the bandwidth exhaustion problem.

DK Photonics offers a wide selection of WDM/CWDM/DWDM devices, like CWDM Mux/Demux, CWDM OADM, DWDM Mux/Demux, DWDM OADM, Filter WDM and so on. DK Photonics 1310/1490/1550 WDM devices based on thin-film filter technology are design to address the precise requirements from the FTTP market. Strong coating and passive device packaging capabilities feature these WDMs with excellent optical performance, good reliability and ultra-compact size.

Something you should know about CWDM DWDM and OADM

CWDM/DWDM Mux/Demux and OADM are all fit in with Passive. CWDM and DWDM technology produce an efficient strategy to share one set of fiber strands and hang together various communications interfaces, simply by using different wavelengths of light for each channel. Thus they could expand the proportions from the network without laying more fiber. And that i want to introduce the actual basical description of CWDM Mux/Demux, DWDM Mux/Demux and OADM.

As you know, Mux (Multiplexer) products combine several data signals into one for transporting over the single fiber. Demux (Demulitplexer) separates the signals at the opposite end. Each signal are at an alternative wavelength.

CWDM Mux/Demux

The Coarse Wavelength Division Multiplexing-CWDM Mux/Demux is often a flexible plug-and-play network solution, which helps insurers and enterprise companies to affordably implement denote point or ring based WDM optical networks. CWDM Mux/demux is perfectly suitable for transport PDH, SDH / SONET, ETHERNET services over WWDM, CWDM and DWDM in optical metro edge and access networks. CWDM tools are widely used in less precision optics and lower cost, un-cooled lasers with lower maintenance requirements. Weighed against DWDM and Conventional WDM, CWDM is a bit more affordable and much less power usage of laser devices. CWDM Multiplexer Modules can be found in 4, 8 and 16 channel configurations. These modules passively multiplex the optical signal outputs from 4 excessively electronic products, send on them somebody optical fiber and de-multiplex the signals into separate, distinct signals for input into gadgets along the opposite end for your fiber optic link.

DWDM Mux/Demux

The Dense Wavelength Division Multiplexing-DWDM Mux/Demux Modules are built to multiplex multiple DWDM channels into 1 or 2 fibers. Depending on type CWDM Mux/Demux unit, with optional expansion, can transmit and receive around 4, 8, 16 or 32 connections of standards, data rates or protocols more than one single fiber optic link without disturbing the other person. DWDM MUX/DEMUX modules provides best and low-cost bandwidth upgrade on your current fiber optic communication networks.

OADM

OADM(Optical Add-Drop Multiplexer) is often a device utilized in WDM systems for multiplexing and routing different channels of fiber into or out of a single mode fiber (SMF). OADM is made to optically add/drop one or multiple CWDM/DWDM channels into one or two fibers, provides capacity to add or drop an individual wavelength or multi-wavelengths from the fully multiplexed optical signal. This enables intermediate locations between remote sites gain access to the regular, point-to-point fiber segment linking them. Wavelengths not dropped pass-through the OADM and continue on in direction of the remote site. Additional selected wavelengths can be added or came by successive OADMS if required.

What is WDM? What Is the Difference Between DWDM and CWDM Optical Technologies?

What is WDM?

In the same optical fiber at the same time can let two or more than two wavelength signal transmit and receive information through different optical channel, called wavelength division multiplex, referred to as WDM. Wavelength division multiplexing includes frequency division multiplexing and wavelength division multiplexing. Optical frequency division multiplexing (FDM) technology and optical wavelength division multiplexing (WDM) technology has no obvious difference, because the light is part of the electromagnetic wave, frequency and wavelength of light have a single correspondence. Usually also can understand so, optical frequency division multiplexing mean subdivision of optical frequency, very dense optical channel. Wavelength division multiplexing means divided frequency of light, light channel far apart, even in the optical fiber with different window.

The general application of division multiplexing wavelength is respectively using a wavelength division multiplexer and demultiplexer arranged at both ends of the optical fiber, coupling and separation of different wavelength. The main four types of WDM are fused biconical taper type, dielectric film type, FBG type and planar waveguide grating type .The main characteristic is the insertion loss and isolation. Usually, the optical link using wavelength division multiplexing equipment, increase the amount of optical link loss is called WDM insertion loss. When the wavelength transmission through the same optical fiber, the D-value between the splitter input mixed power and the output end of the fiber power is called isolation.. The following are characteristics and advantages of optical wavelength division multiplexing technical:

(1) Make full use of low loss band fiber, increase the transmission capacity of optical fiber, the physical limit of an optical fiber for transmitting information doubled to several times. At present, we only use the low loss optical fiber spectrum (1310nm-1550nm) a few, WDM can fully utilize the huge bandwidth of single-mode fiber is about 25THz, the transmission bandwidth is sufficient.

(2) There are ability to transmit two or more than two asynchronous signal in the same optical fiber ,there are compatible for digital and analog signals, has nothing to do with the data rate and modulation mode, the middle line can be removed or added channel.

(3) About the optical fiber system that has built, especially early laying optical cable that core number not much, as long as the original system power is margin, we can increase the capacity; realize the transmission of multiple one-way or two-way signals without making big changes to the original system, so it has strong flexibility.

(4) Due to the large number of reducing use amount of the fiber, it can greatly reduce the construction cost, because the fiber quantity is less, when a fault occurs, the recovery is also fast and convenient.

(5) Sharing of active optical devices, the cost of transmission of multiple signals or increase new business will reduce.

(6)The active devices in the system have been substantially reduced, which improves the reliability of the system. At present, because of the light multi carrier division multiplexing of optical transmitter, optical receiver equipment’s requirements higher, technology implementation has certain difficulty, also multiple core cable used in traditional broadcast television transmission business does not appear especially shortage, so the practical application of WDM is still not much. However, with the development of CATV integrated service development, the growing demand for network bandwidth, all kinds of selective service upgrade and network implementation economic cost considerations and so on, the characteristics and advantages of WDM in the CATV transmission system gradually emerged, showing broad application prospects, even influence the development pattern of CATV network.

What Is the Difference Between DWDM and CWDM Optical Technologies?

DWDM (dense wavelength division multiplexing) is undoubtedly the first choice technology in the field of fiber optic applications today, But the cause of high cost make many do not bounteous operators hesitating. Is there a lower cost for using the wavelength division multiplexing technology? In the face of this demand, CWDM (coarse wavelength division multiplexing) emerges as the times require.

CWDM, just as its name implies, is a dense wavelength division multiplexing next of kin, the difference between CWDM and DWDM mainly has two points: first, the CWDM carrier channel spacing is wider, therefore, light in a single fiber can reuse about 5 to 6 wavelengths, that is where the “dense” and “coarse” appellation come from; Two, CWDM modulation laser using uncooled laser, but DWDM is used in cooling laser. Cooling laser using temperature tuning, uncooled laser adopts electronic tuning. Because the range of temperature distribution is nonuniform in a very wide wavelength, so the temperature tuning is very difficult to realize, the cost is very high. CWDM avoids this problem, so it greatly reduces the cost; the whole CWDM system cost only 30% of DWDM.

CWDM provides a very high access bandwidth with a low cost, suitable for point to point, Ethernet, SONET rings and all kinds of popular network structure, especially suitable for short distance, high bandwidth, access point intensive, communication applications, such as network communication between the building or building. It is particularly worth mentioning is that CWDM with the use of PON (passive optical network).PON is a cheap, one-point to multi-point optical fiber communication mode, in combination with the CWDM, each individual wavelength channel can be used as virtual optical link of PON, Implementation of broadband data transmission between center node and multiple distributed nodes.

There are several companies are offering CWDM related products at present. However, CWDM is a product of cost and performance tradeoffs; inevitably there are some performance limitations. Industry experts point out, at present the CWDM have four following disadvantages: first, CWDM in a single fiber support multiplexing wavelength number is minor, leading to future expansion cost is high; second, multiplexing, multiplexing equipment cost should also be reduced, the device cannot be simply modified of DWDM corresponding equipment; third, CWDM does not apply to metropolitan area network, the distance between metropolitan area network nodes is short , the money that operators use in CWDM equipment expansion can be used to laying more fiber, and get better effect; fourth, CWDM has not yet formed standards.

What’s more, something about the WDM products.

(1)CWDM Mux/Demux module

CWDM Mux and CWDM Demux are designed to multiplex multiple CWDM channels into one or two fibers. The core of CWDM Module application is the passive MUX DEMUX unit. The common configuration is 1×4, 1×8, 1×16 channels. Available in 19″ Rack Mount or LGX module package. Optional wide band port is available to multiplex with CWDM Channels wavelength.

(2)DWDM Mux/Demux Modules

DWDM Mux and DWDM DeMux are designed to multiplex multiple DWDM channels into one or two fibers. The common configuration is 4, 8, 16 and 40 channels. These modules passively multiplex the optical signal outputs from 4 or more electronic devices, send them over a single optical fiber and then de-multiplex the signals into separate, distinct signals for input into electronic devices at the other end of the fiber optic link

(3)Optical Splitter– a important component in EPON network

Optical splitter in optical communication era is a component of EPON network construction, is a connection of OLT and ONU passive device.

Its function is to distribute the downlink data, and focus on the uplink data. Optical splitter has an upstream optical interface, a plurality of downlink optical interface. Optical signals from the upstream optical interface over was assigned to the downstream optical interface out all transmissions, optical signals from the downlink optical interface over being allocated to uplink optical interface out transmission only. The light intensity signal downlink optical interface of each can be same, can also be different.

Multiplexer and demultiplexer

In telecommunications and computer networks, multiplexing (muxing) is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium. The goal is to share an expensive resource. For instance, in telecommunications, several telephone calls may be carried using one wire.

The multiplexed signal is transmitted over a communication channel, which may be an actual transmission medium. The multiplexing divides the capacity from the high-level communication channel into several low-level logical channels, one for every message signal or data stream to be transferred. A reverse process, known as demultiplexing, can extract the original channels around the receiver side. A tool that performs the multiplexing is known as multiplexer (Mux), along with a device that performs the reverse process is called a demultiplexer (Demux).

In electronics, a multiplexer is really a device that selects one of several analog or digital input signals and forwards the selected input right into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send towards the output. Multiplexers are mainly used to increase the quantity of data that can be sent within the network within a specific amount of time and bandwidth. A multiplexer can also be called a data selector. An electronic multiplexer makes it possible for several signals to share one device or resource. Conversely, a demultiplexer is a device going for a single input signal deciding on one of several data-output-lines, which is connected to the single input. A multiplexer is often combined with a complementary demultiplexer on the receiving end. A digital multiplexer can be viewed as like a multiple-input, single-output switch, and a demultiplexer like a single-input, multiple-output switch. The schematic symbol for a multiplexer is an isosceles trapezoid with the longer parallel side containing the input pins and also the short parallel side containing the output pin. The schematic around the right shows a 2-to-1 multiplexer on the left and an equivalent switch on the right. The sel wire connects the specified input towards the output.

In the fiber optic area, a WDM system also utilizes a multiplexer in the transmitter to join the signals together, and a demultiplexer in the receiver to separate them apart. WDM systems are divided into different wavelength patterns, CWDM and DWDM. There are different Mux Demux for every of these.

The DWDM equipment, a DWDM multiplexer, actually contains one wavelength converting transponder for every wavelength signal it’ll carry. The wavelength converting transponders get the input optical signal, convert that signal into the electrical domain, and retransmit the signal utilizing a 1550 nm band laser. Additionally, it contains an optical multiplexer, which takes the different 1550 nm band signals and places them onto a single fiber. And also the DWDM demultiplexer breaks the multi-wavelength signal back into individual signals and outputs them on separate fibers for client-layer systems to detect. DWDM Mux and DWDM Demux are designed to multiplex DWDM channels into one or two fibers. The most popular configuration is 4, 8, 16 and 32 channels. The DWDM modules passively multiplex the optical signal outputs from 4 or more electronic devices, send on them a single optical fiber and then de-multiplex the signals into separate, distinct signals for input into electronics in the opposite end from the fiber optic link.

At the same time frame, there are CWDM multiplexer demultiplexer (CWDM Mux and CWDM Demux). They’re made to multiplex multiple CWDM channels into a couple of fibers. The core of CWDM Module application may be the passive Mux/Demux unit. The most popular configuration is 4, 8, and 16 channels. Optional wide band port for existing 1310nm or 1550nm port is available to multiplex with these CWDM Channels. Along with the CWDM transceiver series or the wavelength converter series, the bandwidth of the fiber may be used in a economical way.