Optical receivers are used in optical communication link to receive the optical signal and convert it to electrical signal for further processing. A receiver essentially contains a detector to detect incoming optical signals and an interface circuit to perform conversion.
Optical detectors used in receivers are usually PIN diodes or Avalanche photodiodes. Important characteristics of a receiver are receiver sensitivity and the dynamic range.
Receiver sensitivity is the lowest optical power level that can be detected even with conditions such as signal to noise ratio, bit error rate etc.The sensitivity of a PIN detector is typically -55 to -40 dBm. Sensitivity of an Avalanche photodiode or APD is typically in the range of -65 to -40 dBm. The sensitivity depends on transmission speed.
Dynamic range is the range of power level within which the optical detector operates properly. Extra attenuators shall be used if the dynamic range of a receiver used in short distance communication is too small. This often happens in CATV applications.