As a passive CWDM device, Coarse Wavelength Division Multiplexer (CWDM) is a low-cost WDM transmission technology for the metropolitan area network access layer. In principle, CWDM uses an optical multiplexer to multiplex optical signals of different wavelengths to a single optical fiber for transmission. At the receiving end of the link, the mixed signals in the optical fiber are decomposed into signals of different wavelengths with the help of an optical demultiplexer and connected to the corresponding receiving equipment.
CWDM adopts thin-film filter technology with good wavelength stability. It can be configured and upgraded according to requirements. The product has the characteristics of low insertion loss, high channel isolation, wide bandwidth, and low-temperature sensitivity.
It is generally divided into 4-channel, 8-Channel, 16 channel, or up to 18 channel coarse wavelength division multiplexers. Due to the requirement of low insertion loss of coarse wavelength division system, when there are many channels, the module can add jump chips to reduce the insertion loss of each channel.
CWDM solves the two problems of optical fiber shortage and multi-service transparent transmission. It is mainly used in metropolitan area network convergence and access layer and It has been widely used in man transmission and CATV systems. It can build a network and carry out services in a short time.
The common CWDM division packaging forms include ABS box, LGX Box, and 19 inch 1U chassis
Feature | CWDM | DWDM |
Channel Spacing | 20 nm | 0.8 nm (100 GHz) or 0.4 nm (50 GHz) |
Wavelength Range | 1270 nm to 1610 nm | 1525 nm to 1565 nm (C band), 1570 nm to 1610 nm (L band) |
Number of Channels | Up to 18 | 40, 80, or more |
Transmission Distance | Up to 160 km | Up to thousands of km with amplification |
Modulation Laser | Uncooled laser | Cooled laser |
Bandwidth | Max 400 Gbps | Over 1 Tbps |
Application | Cable TV, FTTP, cost-effective data transmission | Telecom, long-distance, high-bandwidth, data centers, DCI |
CWDM is suited for shorter distances and has a wider channel spacing, making it a cost-effective solution for metropolitan and access networks.
DWDM offers higher channel density and is designed for long-distance, high-capacity transmission, but at a higher cost and complexity.