Tag Archives: WDM

Economically Increase Network Capacity With CWDM Mux/DeMux

As the demands for voice, video and data networks are increasing dramatically, more bandwidth and higher transmission speed over long distances are needed. To meet these demands, it means that service providers should depend on more fiber optics which definitely cause more costs for optical devices. But they apply Wavelength Division Multiplexing (WDM) technologies which is a cost-effective way to increase capacity on the existing fiber infrastructure.

CWDM Technology

WDM technology multiplexes multiple optical signals onto a single fiber by suing different wavelengths, or colors, of light. WDM can expand the network capacity using existing fiber infrastructure in an economical way. It includes CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing).

CWDM is a technology multiplexing 16 channels onto one single fiber between the wavelengths from 1270 nm to 1610 nm. It’s designed for city and access network. Since the channel spacing is 20 nm, CWDM is a more cost-effective method to maximize existing fiber by decreasing the channel spacing between wavelengths. CWDM is a passive technology, therefore, CWDM equipment needs no electrical power.


Figure 1

CWDM technology has been applied into wide areas, such as CWDM optical transceivers, CWDM OADM and CWDM Mux/DeMux. CWDM Mux/DeMux modules are multiplexers and demultiplexers which provide long distance coverage with premium optical technology to enhance fiber optic systems. It multiplexes signals of different wavelengths on one single fiber and demultiplexes wavelengths to individual fibers. CWDM Mux/DeMux can offer low-cost bandwidth and upgrade the existing system without leading spare costs on more fibers. CWDM Mux/DeMux can hold up to 18 channels of different standards (for example, Fibre Channel, Gigabit Ethernet) and data rates over one fiber optic link without interruption. FS.COM offers a full series of CWDM Mux/DeMux, including 2, 4, 8, 9, 12, 16, 18 channels with or without monitor port and expansion port in 1RU 19” rack chassis or pigtailed ABS module. The following will show you how to use a 18-channel CWDM Mux/DeMux to increase the data rates up to 180 Gbps on a fiber pair.

In Figure2, all Cisco compatible 10G CWDM SFP+ 1270-1610 nm 40km DOM transceivers on the switch are connected with the CWDM Mux/DeMux by LC-LC fiber patch cords. This CWDM Mux/DeMux has 18 channels and is designed as 1 RU rack mount size, covering the wavelengths from 1270 nm to 1610 nm and supporting LC UPC port. During the long distance transmission, only one single-mode armored LC fiber patch cord is needed to achieve 180 Gbps by connecting the two 18-channel CWDM Mux/DeMux. Thus, it greatly saves the cost for increasing the bandwidth on the existing fiber infrastructure.


Figure 2

FMU CWDM Mux/Demux

To increase the capacity, it requires more space and cable management is also a big trouble. So Fiberstore independently researched and developed FMU CWDM Mux/DeMux to solve this problem. We provide FMU 16-ch 1U Rack CWDM MUX/DEMUX specially designed as 2-slot plug and play style, which allows you to add or remove fiber fiber optic cables and plug-in-modules freely according to your applications. There are two separate CWDM plug-in modules. One is high band (1470nm-1610nm) module with an expansion port and the other is low band (1270nm-1450nm, skip 1390nm, 1410nm) module without expansion port. Via this expansion port, channels can be expanded over one pair of fiber without interruption. You can also insert two CWDM Mux/DeMux FMU-plug-in modules without expansion port for two separated 8-channel connections. Besides, you can mix CWDM and DWDM system by adding CWDM Mux/DeMux FMU-plug-in modules and DWDM Mux/DeMux FMU-plug-in modules with matching wavelengths.


Figure 3

FS.COM FMU Plug-in Modules

The table below lists both single fiber and dual fiber FMU plu-in modules for 2-slot CWDM Mux/DeMux. You can choose suitable modules according to you specific requirements. Custom service is available, too.

ID# Description
30431 2, 4, 5, 8, 9 Channels, CWDM Mux Demux, Single Fiber, Type A, Plug-in Module
30447 2, 4, 5, 8, 9 channels, CWDM Mux Demux, Single fiber, type B, Plug-and-play module
43553 4 Channels 1490-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43554 4 Channels 1470-1590nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
48393 4 Channels 1470-1590nm Single Fiber CWDM Mux Demux with Expansion Port, FMU Plug-in Module, LC/UPC
48394 4 Channels 1490-1610nm Single Fiber CWDM Mux Demux with Expansion Port, FMU Plug-in Module, LC/UPC
43779 8 Channels 1310-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43780 8 Channels 1290-1590nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43699 9 Channels 1290-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43711 9 Channels 1270-1590nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
30414 2, 4, 5, 8, 9 Channels, CWDM Mux Demux, Dual Fiber, Plug-in Module
42944 4 Channels 1510-1570nm Dual Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
42972 4 Channels 1270-1330nm Dual Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
42973 4 Channels 1510-1570nm Dual Fiber CWDM Mux Demux with Expansion Port, FMU Plug-in Module, LC/UPC
42945 8 Channels 1290-1430nm Dual Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43097 8 Channels 1470-1610nm Dual Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
43099 8 Channels 1470-1610nm Dual Fiber CWDM Mux Demux with Expansion Port, FMU Plug-in Module, LC/UPC

If you would like to increase your network bandwidth while spend less money on changing existing infrastructure, CWDM Mux/DeMux is an economical solution. FS.COM brings you high quality CWDM Mux/DeMux module and newly self-developed FMU 2-slot CWDM Mux/DeMux modules & FMU plug-in modules. For detailed information, please visit our site www.fs.com or contact us through sales@fs.com.

A Wise Decision to Choose DWDM Mux/DeMux

The advent of big data requires for highly efficient and capable data transmission speed. To solve the paradox of increasing bandwidth but spending less, WDM (wavelength division multiplexing) multiplexer/demultiplexer is the perfect choice. This technology can transport extremely large capacity of data traffic in telecom networks. It’s a good way to deal with the bandwidth explosion from the access network.


WDM stands for wavelength division multiplexing. At the transmitting side, various light waves are multiplexed into one single signal that will be transmitted through an optical fiber. At the receiver end, the light signal is split into different light waves. There are 2 standards of WDM: coarse wavelength division nultiplexing (CWDM) and dense wavelength division multiplexing (DWDM). The main difference is the wavelength steps between the channels. For CWDM this is 20nm (course) and for DWDM this is typically 0.8nm (dense). The following is going to introduce DWDM Mux/Demux.

DWDM Technology

DWDM technology works by combing and transmitting multiple signals simultaneously at different wavelengths over the same fiber. This technology responds to the growing need for efficient and capable data transmission by working with different formats, such as SONET/SDH, while increasing bandwidth. It uses different colors (wavelength) which are combined in a device. The device is called a Mux/Demux, abbreviated from multiplexer/demultiplexer, where the optical signals are multiplexed and de-multiplexed. Usually demultiplexer is often used with multiplexer on the receiving end.


Mux selects one of several input signals to send to the output. So multiplexer is also known as a data selector. Mux acts as a multiple-input and single-output switch. It sends optical signals at high speed over a single fiber optic cable. Mux makes it possible for several signals to share one device or resource instead of having one device per input signals. Mux is mainly used to increase the amount of data that can be sent over the network within a certain amount of time and bandwidth.

Demux is exactly in the opposite manner. Demux is a device that has one input and more than one outputs. It’s often used to send one single input signal to one of many devices. The main function of an optical demultiplexer is to receive from a fiber consisting of multiple optical frequencies and separate it into its frequency components, which are coupled in as many individual fibers as there are frequencies.


DWDM Mux/Demux modules deliver the benefits of DWDM technology in a fully passive solution. They are designed for long-haul transmission where wavelengths are packed compact together. FS.COM can provide modules for cramming up to 48 wavelengths in 100GHz grid(0.8nm) and 96 wavelengths in 50GHz grid(0.4nm) into a fiber transfer. ITU G.694.1 standard and Telcordia GR1221 are compliant. When applied with Erbium Doped-Fiber Amplifiers (EDFAs), higher speed communications with longer reach (over thousands of kilometers) can be achieved.

Currently the common configuration of DWDM Mux/Demux is from 8 to 96 channels. Maybe in future channels can reach 200 channels or more. DWDM system typically transports channels (wavelengths) in what is known as the conventional band or C band spectrum, with all channels in the 1550nm region. The denser channel spacing requires tighter control of the wavelengths and therefore cooled DWDM optical transceiver modules required, as contrary to CWDM which has broader channel spacing un-cooled optics, such as CWDM SFP, CWDM XFP.

DWDM Mux/Demux offered by FS.COM are available in the form of plastic ABS module cassette, 19” rack mountable box or standard LGX box. Our DWDM Mux/Demux are modular, scalable and are perfectly suited to transport PDH, SDH / SONET, ETHERNET services over DWDM in optical metro edge and access networks. FS.COM highly recommends you our 40-CH DWDM Mux/DeMux. It can be used in fiber transition application as well as data center interconnection for bandwidth expansion. With the extra 1310nm port, it can easily connect to the existing metro network, achieving high-speed service without replacing any infrastructure.



With DWDM Mux/DeMux, single fibers have been able to transmit data at speeds up to 400Gb/s. To expand the bandwidth of your optical communication networks with lower loss and greater distance capabilities, DWDM Mux/DeMux module is absolutely a wise choice. For other DWDM equipment, please contact via sales@fs.com.

WBMMF – Next Generation Duplex Multimode Fiber in the Data Center

Enterprise data center and cloud operators use multimode fiber for most of their deployments because it offers the lowest cost means of transporting high data rates for distances aligned with the needs of these environments. The connections typically run at 10G over a duplex multimode fiber pair—one transmit (Tx) fiber and one receive (Rx) fiber. Upgrading to 40G and 100G using MMF has traditionally required the use of parallel ribbons of fiber. While parallel transmission is simple and effective, continuation of this trend drives higher cost into the cabling system. However, a new generation of multimode fiber called WBMMF (wideband multimode fiber) is on the way, which can enable transmission of 40G or 100G over a single pair of fibers rather than the four or ten pairs used today. Now, let’s get close to WBMMF.

What Is Wideband Multimode Fiber?
WBMMF is a new multimode fiber type under development that will extend the ability of conventional OM4 multimode fiber to support multiple wavelengths. Unlike traditional multimode fiber, which supports transmission at the single wavelength of 850 nm, WBMMF will support traffic over a range of wavelengths from 850 to 950 nm. This capability will enable multiple lanes of traffic over the same strand of fiber to transmit 40G and 100G over a single pair of fibers and to drastically increase the capacity of parallel-fiber infrastructure, opening the door to 4-pair 400GE and terabit applications. Multimode fiber continues to provide the most cost-effective platform for high bandwidth connectivity in the data center, and with the launch of the WBMMF solution, that platform has been extended to support higher speeds with fewer fibers and at greater distances.

Wideband Multimode Fiber

What Is the Technology Behind WBMMF?
WBMMF uses short wavelength division multiplexing (SWDM) to significantly increase its transmission capacity by four times. WDM technology is well known for its use in single-mode transmission, but has only recently been adapted for use with vertical cavity surface-emitting lasers (VCSELs), which have been proven in high-speed optical communications and are widely deployed in 10G interconnection applications. SWDM multiplexes different wavelengths onto duplex MMF utilizing WDM VCSEL technology. By simultaneously transmitting four VCSELs, each operating at a slightly different wavelength, a single pair WBMMF can reliably transfer 40G (4x10G) or 100G (4x25G). The use of SWDM then enables WBMMF to maintain the cost advantage of multimode fiber systems over single-mode fiber in short links and greatly increases the total link capacity in a multimode fiber link.


Why Does WBMMF Make Sense?
In order to increase transmission speeds up to 10G or 25G, transceiver vendors simply increased the speed of their devices. When 40G and 100G standards were developed, transmission schemes that used parallel fibers were introduced. This increase in fiber count provided a simple solution to limitations of the technology available at the time. It was accepted in the industry and allowed multimode links to maintain a low cost advantage. However, the fiber count increase was not without issues. At some point, simply increasing the number of fibers for each new speed became unreasonable, in part because the cable management of parallel fiber solutions, combined with the increasing number of links in a data center, becomes very challenging. Please see the picture below. Usually, 40G is implemented using eight of the twelve fibers in an MPO connector. Four of these eight fibers are used to transmit while the other four are used to receive. Each Tx/Rx pair is operating at 10G. But if we use WDMMF, two fibers are enough. Each Tx/Rx pair can transmit 40G by simultaneously transmitting four different wavelengths. This enables at least a four-fold reduction in the number of fibers for a given data rate, which provides a cost-effective cabling solution for data center.

Parallel fibers vs WBMMF

WBMMF is born at the right moment to meet the challenges associated with escalating data rates and the ongoing need to build cost-effective infrastructure. Besides, WBMMF will support existing OM4 applications to the same link distance. Optimized to support wavelengths in the 850 nm to 950 nm range to take advantage of SWDM, WBMMF ensures not only more efficient support for future applications to useful distances, but also complete compatibility with legacy applications, making it an ideal universal medium that supports not only the applications of the present, but also those of the future.

Original article source: http://www.cables-solutions.com/wbmmf-next-generation-duplex-multimode-fiber-in-the-data-center.html

Link Budget Evaluation Over SMF and MMF

Evaluating a link budget is equivalent to calculating the total loss suffered by a transmitted signal along fiber channels with the minimum receiver power to maintain normal operation. Calculating the link budget helps network architects to identify the feasibility of a physical-layer deployment.

Optical fibers come in several different configurations, each ideally suited to a different use or application. Early fiber designs that are still used today include single-mode fiber (SMF) and multimode fiber (MMF). And the most common optical communication data links include point-to-point transmission, WDM and amplified transmission. This article depicts the rules to be applied in order to evaluate link budget of these optical transmissions over SMF and MMF.

Link Budget for Point-to-Point Transmissions over Multimode Fibers

In this first case, the rule is fairly simple. A few parameters need to be taken into account:
● The minimum transmit power guaranteed (minTx), expressed in dBm
● The minimum receive power required (minRx), expressed in dBm
● The loss of optical connectors and adapters (L), expressed in dB
● The number of connectors and adapters (n)
● The normalized fiber loss (FL), expressed in dB/km
● The reach or distance to be achieved (d), expressed in km
With these parameters, the link budget (LB) expressed in dB is given as follows:
● (LB) = (minTx) – (minRx)
This value needs to be compared to the total loss (TL) suffered by the transmitted signal along the given link, and expressed in dB:
● (TL) = n*(L) + d*(FL)
If LB is greater than TL, then the physical deployment is theoretically possible.
In these calculations n is at least equal to 2 since there are a minimum of 2 connectors at each end, L is typically around 0.5 to 1 dB, and FL is of about 1 to 1.5 dB per km.

Link Budget for Point-to-Point Transmissions over Single-mode Fibers

At first, you need to know that the lasers deployed in optical communications typically operate at or around 850 nm (first window), 1310 nm (second window), and 1550 nm (third and fourth windows). In this second case, the calculations are exactly similar to the previous case. Only the numerical values will differ. For single-mode point-to-point transmissions, n is at least equal to 2, L is typically around 0.3 to 0.5 dB, and FL is of about 0.4 dB per km in the second window and about 0.25 dB per km in the third window.

The following drawings show the power budget of a 2km hybrid multimode/singlemode link with 5 connections (2 connectors at each end and 3 connections at patch panels in the link) and one splice in the middle.

power budget

Link Budget for WDM and Amplified Transmissions over Single-mode Fibers

In the case of WDM transmissions, passive modules are used to multiplex and demultiplex various wavelengths respectively before and after the signal propagates along the fiber channel. These passive modules introduce additional insertion losses suffered by the signal transmitted.

Additionally, the signal may be amplified and compensated for dispersion, and in this case, the amplifier gain and the dispersion compensation unit’s loss need to be taken into account. Dispersion and OSNR (optical signal noise ratio) penalties suffered by the receiver shall be considered as well.

Therefore all the parameters needed for a proper link budget evaluation are:
● The minimum transmit power guaranteed (minTx), expressed in dB/m
● The minimum receive power required (minRx), expressed in dB/m
● The loss of optical connectors and adapters (L), expressed in dB
● The number of connectors and adapters (n)
● The normalized fiber loss (FL), expressed in dB/km
● The reach or distance to be achieved (d), expressed in km
● The loss of passive add/drop modules (A and D), expressed in dB
● The gain of the amplifier (G), expressed in dB
● The penalty suffered by the receiver (P), expressed in dB
● The loss of a dispersion compensation unit (DCU), expressed in dB With these parameters, (LB) is given as for previous cases:
● (LB) = (minTx) – (minRx)
And the total loss is expressed as follows:
● (TL) = n*(L) + d*(FL) + (A) + (D) – (G) + (DCU) + (P)
Here again, if LB is greater than TL, then the physical deployment is feasible. Please note that for simplicity, only one amplifier, one dispersion compensation unit, and one set of add/drop modules are considered in this example. If more devices are planned to be deployed, their loss or gain should be added or subtracted accordingly in order to calculate TL.

Link budget is a way of quantifying the link performance. And the performance of any communication link depends on the quality of the equipment being used. Thus, when evaluating a link budget, you are supposed to consider the types of applications, the reach to be achieved, as well as the types of optical fibers deployed. For more information about fiber optical link products, please visit FS.COM.

Erbium Doped Fiber Amplifier (EDFA) Used in WDM System

The capacity of fiber optical communication systems has undergone enormous growth during the last few years in response to huge capacity demand for data transmission. With the available wavelength division multiplexing (WDM) equipment, commercial system can transport more than 100 channels over a single fiber. However, increasing the number of channels in such systems will eventually result in the usage of optical signal demultiplexing components with greater values of optical attenuation. Besides, when transmitted over long distances, the optical signal is highly attenuated. Therefore, to restore the optical power budget, it is necessary to implement optical signal amplification. This article may mainly tell you  why EDFA is used in WDM system and how does it work.

Why Use EDFA in WDM System?

EDFA stands for erbium-doped fiber amplifiers, which is an optical amplifier that uses a doped optical fiber as a gain medium to amplify an optical signal. EDFA has large gain bandwidth, which is typically tens of nanometers and thus actually it is enough to amplify data channels with the highest data rates. A single EDFA may be used for simultaneously amplifying many data channels at different wavelengths within the gain region. Before such fiber amplifiers were available, there was no practical method for amplifying all channels between long fiber spans of a fiber-optic link. There are practically two wavelength widows C-Band (1530nm-1560nm) and L-Band (1560nm-1600nm). EDFA can amplify a wide wavelength range (1500nm-1600nm) simultaneously, which just satisfies the DWDM application, hence it is very useful in WDM for amplification.

How Does EDFA Work ?

The basic configuration for incorporating the EDFA in an optical fiber link is shown in the picture below. The signals and pump are combined through a WDM coupler and launched into an erbium-doped fiber (EDF). The amplified output signals can be transmitted through 60-100km before further amplification is required.

Erbium-doped fiber is the core technology of EDFA, which is a conventional silica fiber doped with erbium ions as the gain medium. Erbium ions (Er3+) are having the optical fluorescent properties that are suitable for the optical amplification. When an optical signal such as 1550nm wavelength signal enters the EDFA from input, the signal is combined with a 980nm or 1480nm pump laser through a wavelength division multiplexer device. The input signal and pump laser signal pass through erbium-doped fiber. Here the 1550nm signal is amplified through interaction with doped erbium ions. This can be well understood by the energy level diagram of Er3+ ions given in the following figure.


Where to Buy EDFA for Your WDM System ?

To ensure the required level of amplification over the frequency band used for transmission, it is highly important to choose the optimal configuration of the EDFAs. Before you buy a EDFA, keep in mind that the flatness and the level of the obtained amplification, and the amount of EDFA produced noise are highly dependent on each of the many parameters of the amplifier. Fiberstore provide many kinds of EDFAs, especially the DWDM EDFAs (shown in the picture below), which have many output options (12dBm-35dBm). Besides, they are very professional in optical amplifiers. Whatever doubts you have, they can give a clear reply.


WDM Multiplexer Is an Ideal Component Optimized for WDM Aplications

Wavelength-division multiplexing (WDM) is a technology which allows multiple signals to be transmitted at different wavelengths over a single optical transmission medium. It can dramatically expand the total capacity of an optical network, for many signals are able to be transported simultaneously. This core technology makes optical network capacity to be gradually efficiently increased to meet the higher demand for bandwidth. To construct WDM networks, a wide range of optical components optimized for WDM applications are required to be researched and created. One of the important components is WDM multiplexer.

WDM multiplexer is a electronic device that uses WDM technology. It is able to combine light signals with different wavelengths coming from different fibers on to a single fiber. A multiplexer usually has two signal inputs, one control input and one output. The input end of a WDM multiplexer is coupler that combines all the inputs into one putout fiber. And each channel in a WDM multiplexer is designed to transmit a specific optical wavelength. For example, an 16-channel multiplexer would have the ability to combine sixteen different channels or wavelengths from separate optical fibers onto one optical fiber. And the separated signals will be recovered by another multiplexer called demultiplexer. The following picture shows how the signals are transported.

multiplexer and demultiplexer

WDM multiplexer is available with various configurations such as 2,4, 8, 16, 32, 64, etc. The types of multiplexers can be divided by channel spacing. They can be called CWDM multiplexers, wideband or crossband ones, and DWDM multiplexers, narrowband or dense ones. Compared to DWDM multiplexers, CWDM multiplexers combines signals at fewer channels for its larger channel spacing. CWDM multiplexers is usually with configurations such as 8, 16 and so on, while DWDM multiplexers is commonly with configurations including 32, 96, 128, etc. CWDM multiplexers are able to combine a broad range of wavelengths such as l310 nm and 1550 nm. DWDM multiplexers are able to combines wavelengths with 100 GHz channel spacing. It typically provides a broad range of wavelengths in 1.55-μm region within C-band.

WDM multiplexer, an advanced optical component, is widely used in optical links. It can increase connectivity and bandwidth of processing systems by interconnecting different channels. Most WDM multiplexers employ one of three technologies: arrayed waveguide grating (AWG), filter and dispersive element, primarily diffraction grating. Some multiplexers based on filters exhibit high insertion loss for devices with many channels, which makes them are not suitable in the application of multimode and bi-directional transmission. But the multiplexers with AWG technology offers many advantages over them including low cost for many channels, low loss, little crosstalk, and receiving much attention. With AWG technology, WDM multiplexer is ideal for the application of high throughput optical links in parallel processing and computing.

It is concluded that WDM multiplexer with WDM technology is a key component in optical links and even in the high throughput optical links.