Optical parameters

This guide provides average transmit and receive power ranges for transceiver modules.

Transmit power

Transmit power is the power at which the transmitter of an optical transceiver module transmits optical signals, in dBm.

Receive power

Receive power is the power at which the receiver of an optical transceiver module receives optical signals, in dBm.

Use of attenuators

Transceivers are designed to transmit light pulses at a power level that accounts for loss in the fiber optic cabling, and meets the receiver input thresholds of the link partner optical transceiver.

If you are using a fiber cable with less light loss than expected (for example, in a test environment and you do not have a 40km spool of SMF available), use attenuators to affect the transmit level to within the receive sensitivity of the other transceiver -- you will need to condition both fibers (sends in both directions). If not done, you risk overdriving the Receive end and permanently damaging the transceiver. For example, a 40G ER4 has a highest transmit level of 4.5dBm, but the Receive Sensitivity can be no higher than -4.5dBm. That means there must be at least a 9dBm loss on the light level to be within the standards (4.5 - (-4.5) = 9dBm required).