CWDM & DWDM Mux/Demux Overview

As we all know, WDM (wavelength-division multiplexing) is a method of multiplexing a number of optical carrier signals onto a single optical fiber by using different wavelengths (colors) of laser light. It enables bidirectional communications over one strand of fiber, as well as multiplication of capacity. In a WDM system, a multiplexer (Mux) is used at the transmitter to join the several signals together, and a demultiplexer (Demux) is used at the receiver to split the signals apart. This article will focus on the CWDM & DWDM Mux/Demux.

CWDM Mux/Demux

 

CWDM (coarse wavelength division multiplexing) is an excellent choice for increasing bandwidth capacity while keeping costs down in short-range communication networks. CWDM Mux/Demux modules are bidirectional passive optical multiplexers and demultiplexers, allowing multiple optical signals at different wavelengths to pass through a single optical fiber strand. It can combine up to 18 different wavelength signals from different optical fibers into a single optical fiber, or separates up to 18 different wavelength signals coming from a single optical fiber to 18 separate optical fibers. The following picture shows the front panel of 18 channels 1270-1610nm dual fiber CWDM Mux Demux with monitor port.

DWDM Mux/Demux

 

DWDM (dense wavelength division multiplexing) solution is the preferred option for long-haul transmission. The DWDM Mux/Demux modules deliver the benefits of DWDM technology in a fully passive solution. Usually, they are used for long-distance transmission where wavelengths are packed tightly together over the C-band range of wavelengths, up to 48 wavelengths in 100GHz grid (0.8nm) and 96 wavelengths in 50GHz grid (0.4nm). Currently, the most common configuration of DWDM Mux/Demux is from 8 channels to 96 channels. The following picture shows the front panel of 40 channels C21-C60 dual fiber DWDM Mux Demux with monitor port and 1310nm port, which is ideally suited for high-density add/drop requirements in DWDM networks.

 

Comparison Between CWDM and DWDM System

 

Price difference—CWDM system carries less data, but the cabling used to run is less expensive and less complex. A DWDM system has much denser cabling and can carry a significantly larger amount of data, but it can be cost prohibitive, especially where there is a need for a large amount of cabling in an application.

Transmission distance—DWDM system is designed for longer distance transmission as stated above. They can transmit more data over a significantly larger run of cable with less interference than a comparable CWDM system. If there is a need for transmitting the data over a long range, DWDM system will likely be the best in terms of functionality of the data transmittal and the lessened interference over the longer distances that the wavelengths must travel.

CWDM system cannot transmit over long distances because the wavelengths are not amplified, and therefore CWDM is limited in its functionality over longer distances. Typically, CWDM can travel anywhere up to about 100 miles (160 km), while an amplified DWDM system can go much further as the signal strength is boosted periodically throughout the run. As a result of the additional cost required to provide signal amplification, the CWDM solution is best for short runs that do not have mission critical data.

FS.COM CWDM & DWDM Mux/Demux Solution

 

Multiplexing enables a high density, scalable fiber solution. It allows an increase in the fiber utilization by carrying multiple signals down an individual fiber connection, rather than investing in more fibers. As a professional manufacturer and supplier in telecommunication industry, FS.COM offers a full range of CWDM & DWDM Mux/Demux. Our Mux/Demux modules are designed for the best possible performance levels, which helps to expand the bandwidth of optical communication networks with lower loss and greater distance capacities. They are protocol transparent and perfectly suit various applications, such as PDH, SDH/SONET, Fibre Channel, etc. With different housing options, the end users can easily add CWDM or DWDM capabilities to their existing or new networks. For more details, please visit www.fs.com.

Originally published: www.fiberopticshare.com/cwdm-dwdm-muxdemux-overview.html

 

Differences between CWDM and DWDM

In fiber-optic communications, WDM (wavelength-division multiplexing) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This technique enables bidirectional communications over one strand of fiber as well as multiplication of capacity. Generally, WDM technology is applied to an optical carrier which is typically described by its wavelength.

WDM system uses a multiplexer at the transmitter to join the signals together, and a demultiplexer at the receiver to split the signals apart (see Figure 1). WDM system is very popular in the telecommunication industry because it allows the capacity of the network to be expanded without laying more fiber. By utilizing WDM and optical amplifiers, users can accommodate several generations of technology development in their optical infrastructure without having to overhaul the backbone network. Moreover, the capacity of a given link can be expanded simply by upgrading the multiplexers and demultiplexers at each end.

Figure 1

WDM could be divided into CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing). DWDM and CWDM are based on the same concept of using multiple wavelengths of light on a single fiber but differ in the spacing of the wavelengths, number of channels, and the ability to amplify the multiplexed signals in the optical space. Below part will introduce some differences between CWDM and DWDM system.

Wavelength Spacing

CWDM provides 8 channels with 8 wavelengths (from 1470nm through 1610nm) with a channel spacing of 20nm. While DWDM can accommodate 40, 80 or even 160 wavelengths with narrower wavelength spans which are as small as 0.8nm, 0.4nm or even 0.2nm (see Figure 2).

Figure 2

Transmission Distance

DWDM multiplexing system is capable of having a longer haul transmittal by keeping the wavelengths tightly packed. It can transmit more data over a larger run of cable with less interference than CWDM system. CWDM system cannot transmit data over long distance as the wavelengths are not amplified. Usually, CWDM can transmit data up to 100 miles (160km).

Power Requirements

The power requirements for DWDM are significantly higher. For instance, DWDM lasers are temperature-stabilized with Peltier coolers integrated into their module package. The cooler along with associated monitor and control circuitry consumes around 4W per wavelength. Meanwhile, an uncooled CWDM laser transmitter uses about 0.5W of power.

Price

The DWDM price is typically four or five times higher than that of the CWDM counterparts. The higher cost of DWDM is attributed to the factors related to the lasers. The manufacturing wavelength tolerance of a DWDM laser die compared to a CWDM die is a key factor. Typical wavelength tolerances for DWDM lasers are on the order of ±0.1 nm, while tolerances for CWDM laser die are ±2-3 nm. Lower die yields also drive up the costs of DWDM lasers relative to CWDM lasers. Moreover, packaging DWDM laser die for temperature stabilization with a Peltier cooler and thermister in a butterfly package is more expensive than the uncooled CWDM coaxial laser packing.

To sum up, CWDM and DWDM have different features. Choosing CWDM or DWDM is a difficult decision. We should first understand the differences between them. Fiberstore has various kinds of WDM products, such as 10GBASE DWDM, 40 channel DWDM Mux, CWDM Mux/Demux module and so on. It is an excellent option for choosing CWDM and DWDM equipment.

Article source: www.fiber-optic-components.com/differences-between-cwdm-and-dwdm-2.html