Both technologies put several services on one fiber pair. They differ in how close the wavelengths are, and that changes the channel count, the reach and the cost.
CWDM in short
- Wide 20 nm channel spacing over roughly 1270–1610 nm, so up to 18 channels per fiber pair.
- Uncooled optics and simple passive multiplexers keep the cost low.
- The channels spread far outside the C-band, so EDFAs cannot amplify them: reach is limited by the optical budget of each transceiver.
- A good fit for 1G/10G access and aggregation over short to medium distances with a few services.
DWDM in short
- Narrow 100 GHz or 50 GHz spacing in the C-band: 40, 48, 80 or 96 channels with the catalog AAWG multiplexers.
- EDFAs amplify all channels at once, so long and multi-span routes are possible.
- The natural choice for 100G and above, and for routes that will keep growing.
- The OSP3800 platform documents up to 18 CWDM or 96 DWDM wavelengths (50 GHz), so a network can start with either.
How to decide
Count the services you will need in three years, not today. If it is a handful of 10G links over a short route, CWDM is the economical answer. If you expect 100G services, more than about 8–10 channels, or spans that need amplification, start with DWDM: changing later means replacing the multiplexers and the optics.
A mixed approach
Many regional networks use both. CWDM stays on short access links where a few 1G or 10G services are enough, while DWDM carries the backbone between the main POPs, where 100G services and amplification are needed. Keeping the two separate lets each part grow at its own pace, and the access links can move to DWDM later only where demand justifies it. The same fiber plant serves both, so the decision can be made route by route.
What to send us
The route length and loss, the services today and in three years, and the equipment at each end. We reply within 24 hours with a CWDM or DWDM proposal.