Tag Archives: DWDM

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
68210 4 Channels 1470-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
58215 4 Channels 1270-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
68213 8 Channels 1290-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
68215 9 Channels 1270-1610nm Single Fiber CWDM Mux Demux, FMU Plug-in Module, LC/UPC
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.

DWDM Techonology in Long-haul Optical Networks

In twenty-first century, there is a growing volume of data traffic which requires a higher bandwidth capacity. But this explosion in consumer demand for bandwidth makes long-haul networks cop with fiber exhaust. To respond to this explosive growth in bandwidth demand, many long-haul providers use dense wavelength division multiplexing (DWDM) technology to enhance the capacity of propagating data.

DWDM wavelength

Wave Division Multiplexing: Light in different colors can be combined on the same fiber

DWDM Solution — Efficient for Long-haul Provider

DWDM is an efficient solution for long-haul providers. It can increase the capacity of embedded fiber by first assigning incoming optical signals to specific frequencies within a designated frequency band and then multiplexing the resulting signals out onto one fiber. Compared to CWDM (coarse wavelength division multiplexing), DWDM has smaller channels spacing, enabling more signals with higher precision to be combined on the same fiber. It is typically used for long-haul system for its more channels to transport data. DWDM typically has the capability to transport up to 96 channels (wavelengths) in what is known as the Conventional band or C-band spectrum. Fiberstore provide DWDM Mux/Demux various from 4 channels to 96 channels. For better use at present and in the future, we offer plug-in FMU DWDM Mux/Demux (Check FMU DWDM Mux/Demux). With the advancement of DWDM technology, even 160 channels (wavelengths) can be transported within the same fiber, which allows as many as signals be transported simultaneously. DWDM can also combine multiple optical signals, which makes them be amplified as a group and transported in high speed and large volume. So DWDM technology is one of the best choices for transporting extremely large amounts of data traffic over metro or long distances in optical networks.

dwdm wavelength region

Wavelength Regions

DWDM Solution — Economical for Long-haul Provider

DWDM technology is also an economical solution for long-haul providers. A DWDM infrastructure can increase the distance between network elements, benefiting long-haul providers who look to reduce their initial network investments significantly. The fiber optic amplifier component of the DWDM system also enables long-haul providers to save costs without by taking in and amplifying optical signals without converting them to electrical signals. Furthermore, DWDM can provide a broad range of wavelengths in 1.55-μm region within C-band, which is showed in the picture “Wavelength Regions”. With a DWDM system multiplexing more wavelengths on a singer fiber, carriers can decrease the number of regenerators in a long-distance networks, resulting in fewer interruption and improved capacity with less loss.

Proven to be the optimal way of combining advanced functionality with cost efficient transport, DWDM technology is also friendly-used. The long-haul providers can integrate the DWDM technology easily with existing equipment in the network for the interface is bit-rate and format independent. And as continuous growth in data traffic, the long-haul providers will have an increasing reliance on improved DWDM technology to ensure good capacity of data transmission.

FS.COM DWDM Solution

Fiberstore supplies a complete series of WDM optical network solutions such as multiplexers, amplifiers, transceivers, etc. Especially, Fiberstore produce and stock for a full range of DWDM products to help build and expand fiber optic networks. For example, Fiberstore offers DWDM MUX/DEMUX Modules with 50GHz/100GHz/200GHz channel spacing, DWDM OADM modules with various configurations and DWDM Transceivers (SFP, SFP+, XFP, GBIC, X2, XENPAK) supporting 155Mbps to 10Gbps data transmissions.

For more information including DWDM Mux/Demux insertion loss testing video, FMU&FMT solution, and case study of DWDM multipoint transmission project, you can visit FS.COM long haul DWDM network solution.

Optical Multiplexing for High Speed Communication Systems


Optical transmission uses pulses of light to transmit information from one place to another through an optical fiber. The light is converted to electromagnetic carrier wave, which is modulated to carry information as the light propagates from one end to another. The development of optical fiber has revolutionized the telecommunications industry. Optical fiber has replaced other transmission media such as copper wire since inception, and is mainly used to wire core networks. Today, optical fiber has been used to develop new high speed communication systems that transmit information as light pulses, examples are multiplexers/demultiplexers using the optical multiplexing technology.

What is Multiplexing?

Multiplexer (Mux) is hardware component that combines multiple analog or digital input signals into a single line of transmission. And at the receiver’s end, the multiplexer is known as DeMultiplexer (DeMux)—performing reverse function of multiplexers. Multiplexing is therefore the process of combining two or more input signals into a single transmission. At receiver’s end, the combined signals are separated into distinct separate signal. Multiplexing enhances efficiency use of bandwidth. Here is a figure which shows the principle of optical multiplexing/demultiplexing.

Principle of Optical Multiplexing and DeMultiplexing

Optical Mux and DeMux are required to multiplex and demultiplex various wavelengths onto a single fiber link. Each specific I/O will be used for a single wavelength. One optical filter system can act as both Mux and DeMux. Optical Mux and DeMux are basically passive optical filter systems, which are arranged to process specific wavelengths in and out of the transport system (usually optical fiber). Process of filtering the wavelengths can be performed using Prisms, Thin Film Filter (TFF), and Dichroic filters or interference filters. The filtering materials are used to selectively reflect a single wavelength of light but pass all others transparently. Each filter is tuned for a specific wavelength.

Components of Optical Multiplexer

Generally, an optical multiplexer consists of Combiner, Tap Couplers (Add/Drop), Filters (Prisms, Thin film, or Dichroic), Splitter, and Optical Fiber. Here is a figure that shows the structure of a common optical multiplexer.

Structure of Optical Multiplexer

Optical Multiplexing Techniques

There are mainly three different techniques in multiplexing light signals onto a single optical fiber link: Optical Time Division Multiplexing (OTDM), Wavelength Division Multiplexing (WDM), and Code Division Multiplexing (CDM).

  1. OTDM: Separating wavelengths in time.
  2. WDM: Each channel is assigned a unique carrier frequency; Channel spacing of about 50GHz; Includes Coarse WDM (CWDM) and Dense WDM (DWDM).
    • CWDM: Characterized by wider channel spacing than DWDM.
    • DWDM: Uses a much narrower channel spacing, therefore, many more wavelengths are supported.
  3. CDM: Also used in microwave transmission; Spectrum of each wavelength is assigned a unique spreading code; Channels overlap both in time and frequency domains but the code guide each wavelength.


  • The major scarce resource in telecommunication is bandwidth—users want transmit at more high rate and service providers want to offer more services, hence, the need for a faster and more reliable high speed system.
  • Reducing cost of hardware, one multiplexing system can be used to combine and transmit multiple signals from Location A to Location B.
  • Each wavelength, λ, can carry multiple signals.
  • Mux/DeMux serve optical switching of signals in telecommunication and other field of signal processing and transmission.
  • Future next generation internet.


  • High data rate and throughput: Data rates possible in optical transmission are usually in Gbps on each wavelength; Combination of different wavelengths means more throughput in one single communication systems.
  • Low attenuation: Optical communication has low attenuation compare to other transport system.
  • Less propagation delay.
  • More services offered.
  • Increase Return On Investment (ROI)
  • Low Bit Error Rate (BER)


  • Fiber Output Loss and Dispersion: Signal is attenuated by fiber loss and distorted by fiber dispersion, then regenerator are needed to recover the clean purposes.
  • Inability of current Customer Premises Equipment (CPE) to receive at the same transmission rate of optical transmitting systems (achieving all-optical networks).
  • Optical-to-Electrical Conversion Overhead: Optical signals are converted into electrical signal using photo-detectors, switched and converted back to optical. Optical/electrical/optical conversions introduce unnecessary time delays and power loss. End-to-end optical transmission will be better.

Future Work

  • Research in optical end user equipment: Mobile phones, PC, and other handheld devices receiving and transmitting at optical rate.
  • Fast regeneration of attenuated signal.
  • Less distortion resulting from fiber dispersion.
  • End-to-end optical components: Eliminating the need for Optical-to-Electrical converter and vise versa.


While optical transmission is better compare to other transmission media because of its low attenuation and long distance transmission profile, optical multiplexing is useful in signal processing and transmission by transporting multiple signals using one single fiber link. As the growth of the internet requires fiber optic transmission to achieve greater throughput, optical multiplexing is also useful in image processing and scanning application.

Article Source: http://www.fiberopticshare.com/optical-multiplexing-for-high-speed-communication-systems.html

DWDM play an important role in submarine systems

Advantages of DWDM Multiplexer

DWDM is a very effective means of sharing transmission costs when fiber and other common components, such as optical amplifiers, dominate the overall system cost. The aggregate capacity of a single optical fiber can be increased by either increasing the bit rate or by increasing the number of wavelength channels using DWDM. The former requires development of new high-speed electronics, while DWDM allows fiber and fiber amplfier costs to be shared among all channels, driving down the total system cost per channel. Since information must still be coded onto the wavelength channels, today’s long-haul systems combine time-division multiplexing(TDM) with DWDM, taking advantage of high speed TDM advances to further reduce the system cost per bit per channel.

Both long-haul and undersea systems depend heavily on dense wavelength division multiplexed (DWDM) signals to achieve high-capacity transport.

Current long-haul system development efforts have focused on wide-band DWDM and ultra-long transport. These systems are enabled by new modulation formats, wideband amplification, wideband dispersion compensation and the use of forward error correction coding. Taken as a whole , these systems will deliver the lowest cost per transmitted bit over the longest distance . Optical fiber is an integral component of the entire system. T he fiber’s parameters have a significant impact on both cost and performance and influence the choice of most other components, such as amplifiers and compensators. In fact ,the use of wideband DWDM over ultra-long distances has elevated the fiber requirements in terms of dispersion management, nonlinear performance, distributed gain, spectral loss, and polarization mode dispersion (PMD).


The first applications of fiber optic communication were to carry aggregated voice traffic between major metropolitan areas, such as the trunk lines from Washington, DC to Boston. In the United States, typical distances between major switch centers are on the order of 1600 km, while in Europe, these distances are typically 400 km. However, with the advent of all-optical or photonic switching located at these centers, the transmission distances without electronic regeneration could reach well into the thousands of kilometers in both cases, with the application space for these systems spilling over into the metro and regional networks. Such ultra-long distances have historically been reserved for point-to-point undersea fiber systems where transoceanic distances are typically 10,000 km and 4000 km for Trans-Pacific and Trans- Atlantic routes, respectively. As these distances are approached in terrestrial applications, it is not unreasonable to think of using similar system solutions for land applications.