CWDM VS DWDM Optical Transceiver Modules

WDM is a technology to solve the shortage of optical fiber resources. Its main purpose is to increase the available bandwidth of optical fiber without laying more optical fibers. CWDM and DWDM are two WDM technologies widely used in telecom. They are mainly used in Mux/Demux, which must be used with WDM optical modules. In the literal sense these two technologies are just different in the density of wavelength, but their actual technology and applications are very different. The following “”ribes the differences between CWDM and DWDM optical modules.

1.Channel Spacing

CWDM carrier channel spacing is wider, at 20nm between each wavelength. Therefore, it supports up to 16 wavelength channels transmitted through a fiber at the same time. DWDM carrier channel spacing is narrower, at only 0.2nm, 0.4nm, 0.8nm, or 1.6nm between each wavelength, supporting up to 160 wavelength channels though a fiber at the same time.

2.Wavelength Range

Working wavelength range of CWDM is 1270nm — 1610nm, while that of DWDM is selected from CWDM, including 1525nm — 1565nm (C-band) and 1570nm — 1610nm (L-band).

3.Costs

CWDM modulation laser uses uncooled laser, which is electronically modulated, while DWDM uses cooled laser, which is temperature modulated. Due to the uneven temperature distribution over an optical wavelength range, it is difficult and costly to implement temperature modulation, therefore, the cost of DWDM technology is much higher than that of CWDM.

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