DWDM (Dense Wavelength Division Multiplexing) is the core fiber capacity expansion technology for MAN, DCI and telecom backbone. This article fully compares passive DWDM and active DWDM from system composition, transmission distance, cost, channel capacity, operation maintenance and applicable scenarios, helping network engineers select the optimal fiber multiplexing scheme.

Ⅰ. Basic Concept of DWDM Technology

DWDW is short for dense wavelength division multiplexing. It’s a technology for transmitting multiple signals simultaneously at different wavelengths on the same fiber. It can save a lot of optical fiber resources in long distance transmission applications. DWDM follows ITU-T G.694.1 standard, adopting 0.4nm / 0.8nm narrow channel spacing in C-band low-loss window, supporting up to 96 wavelength channels on single fiber pair, greatly improving single fiber transmission capacity without laying new optical cables.

Ⅱ. What Is Passive DWDM System？

Ⅲ. What Is Active DWDM System？

Active DWDM is a system that contains transponders, the function of the transponder is optical electro optical (OEO) conversion. The management and maintenance of active DWDM system is also more complex, so its operation cost is higher. Active DWDM systems are still widely used in large capacity optical transmission applications.

Complete active DWDM system integrates three core active hardware: EDFA optical amplifier, DCM dispersion compensation module and OEO transponder (3R signal regeneration). It can compensate fiber attenuation and chromatic dispersion, realize signal reshaping, retiming and re-amplification, support ultra-long distance transmission over hundreds or thousands of kilometers.

Both passive DWDM and active DWDM have their own pros and cons, which will be described in detail below.