In fiber optic networks, I understand CWDM technology can multiplex multiple optical signals onto a pair of fibers (or a single one).
But can a single pair of CWDM transceivers be connected directly using a pair of fibers without the use of a multiplexer/demultiplexer? Will they function like regular (non-WDM) transceivers?
If so, can the CWDM modules have mixed wavelengths provided they have full-band receivers?
Mutiplexers arrange multiple wavelengths onto a shared fiber - they don't change the signals. So yes, if the transmitter/receiver wavelengths match you can connect two transceivers with standard patch cable. Depending on the transmission power (for 20+ km parts), attenuators might be required with short cables to avoid blinding or permanently damaging the receiver - check the spec sheet for details.
Transmitters and receivers don't even have to match exactly since most often the receiver accepts a wider wavelength range. That should also be part of the spec sheet.
If you're not very well inside the power & wavelength envelopes you should monitor the error rate to stay within your requirements.
