Photodiode detector with selective frequency response

Claim 1

A photodiode detector, comprising: a substrate; a multilayer structure on a surface of said substrate, said structure comprising a plurality of aligned detector sections; said structure comprising a confining layer on said surface of said substrate and an active layer on said confining layer, said confining layer and said active layer of the same conductivity type and extending homogeneously across said substrate for all the detector sections; said active laye providing a waveguide layer having a portion for each detector with said portions in optical alignment, the active layer having an input end; a further confining layer on said active layer, said further confining layer of a conductivity type opposite to that of said active layer and separated into portions, a portion for each detector section, the portions of said further confining layer electrically isolated from each other; means for applying a reverse bias to each detector section, the bias successively more negative for each successive section from said input end; output means for each section for producing an output signal indicative of photon absorption in said section.