CWDM Channel Plan
CWDM channel plan – full list of channels for CWDM systems, color coding, and how we use them in pairs for bidirectional CWDM systems is explained in this article.
CWDM (Coarse Wavelength Division Multiplexing) is one of the xWDM technologies that allows for achieving greater data throughput and is defined by per ITU-T G.694.2 specification consists but is not restricted to 18 CWDM Channels, divided by wavelengths (λ) evenly spaced 20 nm apart between each channel from 1271 nm to 1611 nm, as shown in Double Fiber CWDM Channel plan table:
| Nominal central wavelengths (nm) | Latch color by wavelength | BIDI Pair | Side |
|---|---|---|---|
| 1271 | 1 | A | |
| 1291 | 1 | B | |
| 1311 | 2 | A | |
| 1331 | 2 | B | |
| 1351 | 3 | A | |
| 1371 | 3 | B | |
| 1391 | 4 | A | |
| 1411 | 4 | B | |
| 1431 | 5 | A | |
| 1451 | 5 | B | |
| 1471 | 6 | A | |
| 1491 | 6 | B | |
| 1511 | 7 | A | |
| 1531 | 7 | B | |
| 1551 | 8 | A | |
| 1571 | 8 | B | |
| 1591 | 9 | A | |
| 1611 | 9 | B |
To use CWDM-based modules, a requirement is to use a MUX/DEMUX unit at each end – additional information can be found at HERE and HERE.
The number of channels for data transmission is dependent on the MUX/DEMUX unit used, as there are two main types Single Fiber (BiDi) CWDM MUX and Double Fiber CWDM MUX (Each CWDM MUX/DEMUX unit channel count and used wavelengths can be customized).
Single Fiber (BiDi) CWDM MUX
Provides the ability to organize up to 9 parallel and independent data streams over a single fiber of single-mode optical fiber, and they are organized in pairs. The first module of the pair is applied at one end of and the second module of the same pair to the other end. For example, the SCMD-9A 1310 nm module will be transmitted to the SCMD-9B 1331 nm module and vice versa. Below, you will find the Single Fiber CWDM Channel plan table:
| BIDI Pair# | A side | B side |
|---|---|---|
| 1 | 1271 | 1291 |
| 2 | 1311 | 1331 |
| 3 | 1351 | 1371 |
| 4 | 1391 | 1411 |
| 5 | 1431 | 1451 |
| 6 | 1471 | 1491 |
| 7 | 1511 | 1531 |
| 8 | 1551 | 1571 |
| 9 | 1591 | 1611 |
Double Fiber CWDM MUX
Doubles the bandwidth as it consists of 18 channels sending and receiving information over two SMF (Single-Mode Fiber) lines (one for sending, one for receiving). On both ends same CWDM channel module transmits data to the other side and receives data from the other side.
