Monolithic integrated microgratings and photodiodes for wavelength demultiplexing

The monolithic integration of micrograting filters and a photodetector array on a silicon substrate for optical wavelength demultiplexing is demonstrated. The demultiplexer is constructed with a series of micrograting filters fabricated by the electron beam direct writing technique in a chalcogenide (amorphous As2S3) film waveguide on a thermally oxidized silicon substrate and a Schottky barrier photodiode array fabricated on the Si surface.The device has the advantages of a high degree of design flexibility, high efficiency, low crosstalk, and very small dimensions. The design considerations and the fabrication process are described and the experimental results are discussed on the demultiplexing characteristics.