What Does WDM and DWDM Meaning

WDM combines multiple optical signals with different wavelengths onto a single fiber. While DWDM uses even more closely spaced wavelengths.
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WDM and DWDM technologies enable high-capacity optical communication systems. WDM combines multiple optical signals with different wavelengths onto a single fiber optic cable. While DWDM uses even more closely spaced wavelengths for higher-capacity transmission.

These technologies are critical for modern telecom networks. It supports high-speed data transmission over long distances. In a WDM system, a multiplexer combines optical signals, and a demultiplexer separates them at the receiving end. DWDM uses up to 80+ channels to transmit data rates up to terabits per second.

WDM and DWDM play a vital role in enabling internet access, video streaming and cloud computing.

wdm meaning

1.What is DWDM

DWDM combines numerous data streams onto a single optical cable by using different light wavelengths.

The term “DWDM” refers to a subset of wavelength-division multiplexing (WDM). Which often inputs 40, 88, 96, or even 160 wavelengths, or channels, onto a single strand of fiber optic cable. It uses the spectrum range between 1530nm and 1625nm, or more frequently the C-band and L-band.


Although each channel in DWDM is only roughly 0.8nm wide. The name “DWDM” refers to its use of denser (tighter) wavelength spacing to fit more channels.

On the other hand, CWDM, uses a wider spectrum of frequencies, with each channel being spaced farther apart.
DWDM has a large number of channels available, which allows it to fit significantly more data onto the cable than CWDM. Which only has channels that are 20nm wide.


Channel Spacing

The spacing is greater in CWDM than DWDM 

Transmission Distance

DWDM can cover a greater distance than CWDM.

Modulation Laser

DWDM system use the cooling laser, while CWDM system use the uncooled laser.


Due to DWDM’s increased popularity, DWDM transceivers cost 20–25% less than CWDM transceivers

Advantages and Disadvantages

he channel spacing is the main distinction between DWDM and CWDM. (CWDM has almost 100 times wider channel spacing).

As a consequence, CWDM becomes a more straightforward technology with advantages and disadvantages of the various systems in terms of price, performance, and other factors.

CWDMLower power consumptionSmaller space requirementsCan use SMF fiber or MMF cableCan use LED’s or Laser’s for powerLarger individual payloads per channelSmaller and cheaper wave filtersCost savings on start-up and expansionLess capacity than DWDMLess rangeRegeneration vs amplificationO, A and M functions are not carrier-class
DWDMMaximum capacity system availableMaximum distance capability with EDFA’sRepeater “amp” sites can be reducedPay as you grow expansionMature O, A and M systems are developedNeed more spaceNeed more powerNeed high accuracy lasers and wave filtersExpensive EDFA’s for amplifiersStart-up costs are more than the equivalent CWDM system

4.DWDM Network Diagram Introduce

Point-To-Point Topology

A point-to-point topology for long-distance transmission typically includes a laser, a fiber optic multiplexer and demultiplexer, fibers, optical amplifiers, and an optical add-drop multiplexer. To meet the high demands on speed, aggregated bandwidth, signal integrity, reliability, and path recovery, this topology places transmitters and receivers hundreds of kilometers apart and uses at least 10 amplifiers between them.

Ring-Configuration Mesh and Star Networks

A DWDM ring network comprises fibers arranged in a ring configuration to fully interconnect nodes. At each node and central station, an OADM is used to insert, split, and add wavelength channels. As the OADW increases, signal loss occurs, which can be compensated for using optical amplifiers. DWDM ring structures are typically used in local or metropolitan areas and can span several tens of kilometers. In this topology, a hub station manages channel allocation to achieve a fully connected network of nodes with OADM.

Transmit and Receive Directions of DWDM Hub

Transmit Direction

The DWDM hub receives various electrical payloads, assigns each channel a wavelength, and modulates it before sending it to its corresponding physical interface. The modulated optical signal is then optically multiplexed and launched into the fiber.

Receive Direction

The DWDM hub decouples a received WDM signal into channels and converts each optically modulated signal into a digital electrical signal. Each signal is then routed to its corresponding electrical interface. However, because the bit rate of each channel varies, each channel requires its own return circuit.

5.How to Choose WDM Manufacturers

At present, the problem of which WDM manufacturer is good on the Internet is full of various advertising and comments, which has left consumers with no choice. As a result, we are very blind in how to choose WDM, but we can analyze which WDM manufacturer is good from the following points?

First, before buying WDM, we must first confirm the qualifications of this manufacturer. Is it a well -known company across the country? What are the qualifications? What is the reputation of the user?

Second, why can the manufacturer provide the production of a high -performance, high -quality WDM to users? It is necessary to confirm the resources of the manufacturer, whether there is strong technical support, generally stable operation for more than ten years.

Third, product performance. Stable performance, more than 95 % of the customer renewal rates, the product performance will not be bad!

Fourth, the price of the product is transparent and not charged. Good ones are too expensive, cheap are not good, so we must weigh the cost -effectiveness of the product. The same performance of the same configuration, basically the price plays a decisive role.

Fifth, after -sales service. Whether the after -sales service can achieve 7*24 hours customer service and technical services, and timely services, users will rest assured.

From the above points, it briefly analyzes some of the basic situations that the WDM manufacturer needs to understand. Of course, first according to your own needs, choose the corresponding products, which can be practical and save more resources!

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