Abstract: A grating coupler is combined with a quantum well index modulator and an optical waveguide to alter the reverse or forward coupling characteristics between two different propagation modes of the system.

Abstract: To overcome the deleterious effects of the nonuniform frequency modulation response in semiconductor lasers due to current injection in direct frequency modulation applications, it has been determined that the linewidth enhancement factor .alpha. be made as large as possible. In one embodiment, distributed Bragg relector lasers well suited for frequency modulation lightwave communication systems are designed to have an integrated feedback element such as a corrugation grating whose effective pitch is selected to cause the Bragg wavelength and, therefore, the laser operating wavelength to be longer than the wavelength at substantially the maximum gain or gain peak in the semiconductor structure. That is, the wavelength of the grating is effectively detuned toward the longer wavelength and lower energy side of the peak of the gain profile.

Abstract: Epitaxial regrowth by vapor phase epitaxy of controlled composition semiconductor material in and around undercut regions of a processed heterostructure wafer permits formation of a ridge waveguide capable of active or passive operation. Subsequent material selective and crystallographically preferential etching is employed to form mirror facets on each end of the ridge waveguide.

Abstract: A grating in the upper reflecting layer (103 or 203) of an antiresonant reflecting optical waveguide is used to extract energy of a selected wavelength from the waveguiding layer (102 or 202) into the reflecting layer. In one embodiment the reflecting layer (103) is designed as a gain medium which is pumped in the region of a grating (120) and optically terminated at each end of the device such that the embodiment serves as a laser having a long cavity provided by the waveguiding layer (102) with the gain provided in the short grating region. In a second embodiment the reflecting layer (203) in the region of a grating (211) has an opposite conductivity dopant from that of the waveguiding layer (202) such that the device in this region may be backbiased to serve as a wavelength selective photodetector. By placing two wavelength photodetectors in tandem with gratings (211 and 212)of different pitches a wavelength demultiplexing photodetector is provided.

Abstract: Epitaxial regrowth by vapor phase epitaxy of controlled composition semiconductor material in and around undercut regions of a processed heterostructure wafer permits formation of a ridge waveguide capable of active or passive operation. Subsequent material selective and crystallographically preferential etching is employed to form mirror facets on each end of the ridge waveguide.

Abstract: A planar silicon dioxide waveguide with low loss for the TE mode has been built on a silicon wafer by separating the waveguide from the substrate with a relatively thin layer of polycrystalline silicon and a layer of silicon dioxide having a combined thickness less than that of the waveguide. The separating layers provide a high antiresonant reflectivity which is operative over a broad range of wavelengths.