Sensitivity Issues of Optical Performance Monitoring

The general requirement for the optical performance monitor from the noise perspective is derived from the fundamental considerations of detector noises. Based upon this understanding, the monitor sensitivity, defined as the minimum input optical power that is required for a specified dynamic range of the SNR monitoring, for example, 30 dB of detectable SNR range, is shown related to the monitor characteristics. It is also pointed out that within the optical layer, the BER as can be measured by a full receiver may not be a good measure of the signal quality.