Multi-photodiodes

摘要

The present invention provides monolithic-structure type photodiodes in which the first photodiode is sensitive to an optical signal having one wavelength and the second photodiode is sensitive to another optical signal having a different wavelength, and in which the first and second photodiodes are superimposed together with an optical filter layer interposed between them which separates a multiplex optical signal into the first and second wavelength signals. Owing to their monolithic structure, the photodiodes of the present invention are extremely useful for receiving multiplex optical signals having a plurality of different wavelengths.