A higher optical power level generally results in a higher SNR and lower BER, indicating a better signal quality. It is measured in decibels (dB) or milliwatts (mW) and plays a crucial role in determining the quality and reliability of optical networks. This indicator is critical to evaluating the performance of optical modules because. The most important elements of optical communication are a transmission medium with extremely low optical attenuation and a highly stable, long-life light source that operates with a small current. Typically both transmitters and receivers have receptacles for fiber optic connectors, so measuring the. Transmit power is the power at which the transmitter of an optical transceiver module transmits optical signals in dBm.