Comparison of Wavelength Division Multiplexing: CWDM vs DWDM vs CCWDM

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Wavelength Division Multiplexing (WDM), including CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing), etc. refers to the simultaneous transmission of multiple signals of different wavelengths coupled on a single fiber.

 

Wavelength Division Multiplexing (WDM), including CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing), etc. Refers to the simultaneous transmission of multiple signals of different wavelengths coupled on a single fiber. It has built-in multiplexers and demultiplexers. The multiplexer (MUX) combines multiple signal wavelengths in one optical fiber at the transmitting end, while the demultiplexer (DEMUX) transmits multiple wavelengths in one optical fiber at the receiving end.

 

The signals of each wavelength are separated. The main purpose of wavelength division multiplexing is to increase the available bandwidth of optical fibers, which can be expanded through WDM without the need to lay more optical fibers. Therefore, it is widely applied by telecommunications companies.

What are the differences between CWDM and DWDM?

 

Wavelength Spacing

CWDM: Wavelength interval ≥20nm, usually 8 bands from 1470 to 1610nm, 20nm interval

DWDM: Wavelength interval <10nm, usually 1550~1570nm band, wavelength interval is 200GHz (1.6nm), 100GHz (0.8nm) or 50GHz (0.4nm)

 

Modulated laser

Under normal circumstances, CWDM modulated lasers use uncooled lasers, while DWDM uses refrigerated lasers. Cooled lasers use temperature tuning, and uncooled lasers use electronic tuning.

 

What are the advantages of CWDM vs DWDM?

 

Compared with DWDM, the biggest advantage of the CWDM system is its low cost. The cost of the device is mainly reflected in filters and lasers. The wide wavelength interval of 20nm makes CWDM have low requirements on the technical indicators of the laser, the structure of the optical multiplexer/demultiplexer is simplified, the yield is improved, and the cost is reduced.

 

DWDM is suitable for long-distance transmission. Compared with CWDM, DWDM with tighter wavelength spacing can carry 8 to 160 wavelengths on an optical fiber, which is more suitable for long-distance transmission. With the help of EDFA (Erbium-doped fiber amplifier), DWDM systems can work within a range of thousands of kilometers.

 

Differences between CWDM and DWDM Application

Based on the above different characteristics of CWDM and DWDM, their application scenarios are also different:

CWDM is applied to access layers of metropolitan area network, telecommunications, enterprise network, campus network, etc.

 

DWDM is suitable for: long-distance, large-capacity long-distance backbone network, or super large-capacity metropolitan area network core node.

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