A method of detecting an optical signal, comprising the steps of: providing an avalanche photodiode (APD) comprising a multiplication region capable of amplifying an electric current, said multiplication region, in operation, having a first ionization rate for electrons and a second ionization rate for holes, wherein said first ionization rate is different in magnitude from said second ionization rate, and exposure to the optical signal causes an impulse response; exposing the APD to a modulating optical signal; providing an external circuit that induces an APD bias to the multiplication region; providing an external circuit for amplifying and processing an electric signal from the avalanche photodiode; and modulating the APD bias in a manner that is correlated with the optical signal.