Abstract: A new MSM photodetector, including a photoabsorbing layer of ternary or quaternary III-V compound semiconductor material, is disclosed. This new photodetector is significant because it exhibits a relatively small dark current and a correspondingly large signal-to-noise ratio. Moreover, the photodetector is readily integrable with electronic integrated circuits and is relatively easy to fabricate.

Abstract: An optical device is disclosed which provides wavelength multiplexing/demultiplexing utilizing a plurality of focusing Bragg reflectors. Each Bragg reflector includes a plurality of confocal (i.e., common foci) elliptical grating lines, with the exit/entrance ports of the input/output waveguides located at the foci of the ellipse. By virtue of the elliptical design, the signal propagating outward from the exit port of the input waveguide will be reflected by the appropriate Bragg reflector and focused into the entrance port of the appropriate output waveguide. When each Bragg reflector exhibits a different ellipticity, but shares one common focal point, optical multiplexing/demultiplexing may be achieved. Optical filtering may be achieved when all Bragg reflectors are designed to have common foci.