GB1519466A - Photodiode detector - Google Patents

Abstract

1519466 Photodetector NORTHERN TELECOM Ltd 14 Aug 1975 [17 Sept 1974] 33937/75 Heading H1K Selective optical frequency response is achieved in a photodiode detector by guiding incident radiation X along an N (or P)-type waveguide layer 22, at the upper surface of which are formed the P-N junctions of a number of similar photodiode detector sections 30, 31, 32, 33, 34. Each photodiode detector section comprises a heterostructure of N (or P)-type layers 21, 22 and P (or N)-type layers 23, 24 epitaxially grown on an N (or P)-type substrate 20. The detector sections are isolated either by etching grooves 48 after forming metal contacts 25, 26, or by doping or proton bombarding the material between the photodetector sections. Application of increasingly negative reverse bias voltages to detector sections 31 to 34 results in the photoresponse characteristics shown in curves 41a to 38a of Fig. 3, with detector section 31 responding to higher energy photons than detector section 34. Equality of bandwidth for each detector may be achieved either by incrementing the reverse bias by increasing amounts for the higher numbered sections or by increasing the lengths of successive sections.