On the problem of broadband signal and noise performance of direct detection optical receivers.

A theory of broadband signal and noise performance of a direct detection optical receiver is presented in this paper. Explicit expressions are given for the gain and noise factor of the optical receiver, consisting of a photodiode followed by a high gain, low noise baseband amplifier. It is assumed that a linear lumped lossless interstage network is placed between the diode and the amplifier to obtain broadband performance from the optical receiver. The constraints imposed by the photodiode on the wideband characteristics of the gain G(R) and noise factor F(R) of the optical receiver are obtained in integral and nonintegral forms.