What is the difference between CWDM and DWDM?

What is the difference between CWDM and DWDM?

What are the differences between Coarse Wave Division Multiplexer (CWDM) and Dense Wave Division Multiplexer (DWDM)? We will analyze from two aspects: band spacing and band.

1. CWDM has 18 bands, ranging from 1270nm to 1610nm, with an interval of 20nm between each band. DWDM has three types of channel spacing as needed: 0.4nm (50GHz), 0.8nm (100GHz), 1.6nm (200GHz), and 100GHz (from C17 to C61, which are the most commonly used and suitable for conventional equipment); 50GHz (from C17 to H61, suitable for high channel devices).

2. DFB lasers are generally used for CWDM with wavelengths ranging from 1470nm to 1610nm. Due to the large channel spacing, CWDM devices and lasers are cheaper than DWDM devices.

3. The spacing between CWDM optical channels is relatively wide, and the number of multiplexed optical wavelengths on the same fiber is less than that of DWDM. This is why the terms “coarse” and “dense” are used;

4. CWDM optical modulation uses non cooled lasers and electronic tuning; DWDM uses cooled laser and temperature tuning.

5. Due to the uneven temperature distribution within a wide range of optical wavelengths, achieving temperature tuning is difficult and costly. CWDM avoids this difficulty and significantly reduces costs. Currently, the cost of CWDM systems is generally only 30% of that of DWDM;

6. The power consumption and physical size of CWDM systems are much smaller than those of DWDM systems.