Abstract: A single-mode optical fiber delay line for filtering at high frequencies utilizes an nth order cascaded recirculating configuration comprised of n+1 couplers. Each coupler has two input fibers and two output fibers. One of the output fibers of each coupler except the last is connected to one of the input fibers of the next coupler in cascade to form a feed-forward path. The other output fiber of each coupler except the first is connected to the other input fiber of the preceding coupler, thus forming a feed-backward path. The feed-forward path and the feed-backward path of adjacent couplers form a delay loop. The delay time in each succeeding delay loop is increased by an incremental delay .tau. equal to the reciprocal of the center frequency of the filter. The delay in the first delay loop is selected to be some multiple m of .tau., where m is an integer selected for a total delay T which permits the use of optical fiber of a length sufficient to avoid bending losses in the optical fiber.

Abstract: A device for combining the outputs of multiple laser sources to produce a single coherent beam with good far-field characteristics. The device includes an optical star coupler having multiple path lengths that are deliberately chosen to be different, by amounts that give rise to an interference pattern that has constructive interference peaks at periodic cycles along a wavelength interval. The optical path-length differences result in the occurrence of at least one wavelength, within the operating range of the lasers, at which all of the lasers will operate. The relationships among the optical path lengths is such that the lasing wavelength is relatively insensitive to phase mismatches along the path lengths.

Abstract: A semiconductor laser device having an array of injection laser diodes with laser cavities coupled to respective inputs of an optical star coupler. The star coupler functions both as a power combiner, to provide a single high-power output, an as a device to couple the laser cavities into a single integrated lasing region, for improved coherence and divergence properties and practically no wavefront distortion.

Abstract: There is disclosed a method by which a three-dimensional horn structure at the end of a channel waveguide in a dielectric chip is produced to facilitate coupling of a fiber optic waveguide by butt coupling techniques. The three-dimensional horn structure is fabricated by localized surface diffusion resulting from superposing a CO.sub.2 laser heating beam on the desired enlarged area while diffusion of the waveguide is taking place or after it has taken place in a controlled ambient furnace atmosphere.

Abstract: The specification describes an optical waveguide device formed by diffusing a metal into a substrate which may be either a semiconductor material or a dielectric material. The substrate is first coated with a liquid composition comprising organo-metallic solutions of the desired metal and silica. The coated substrate is then heated at an elevated temperature for a period of time sufficient to cause the organic portion of the solution to decompose, thereby leaving a composite film comprising an oxide of the desired metal and SiO.sub.2. Upon further heating, the metal from the metal oxide diffuses into the substrate. The residual composite film may be left in place or removed.

Abstract: Apparatus is provided comprising a laser source, a collimating lens, a focussing lens and a detector array disposed along an optical path. A surface acoustic wave transducer is disposed between the collimating and focussing lenses and is adapted to modulate laser light provided by the laser source as a function of the amplitude and frequency of energy applied to the transducer. In accordance with the invention, a 90.degree. Bragg diffraction grating disposed between the collimating lens and the transducer, is adapted for transmitting light of a predetermined frequency and predetermined polarization along the optical path. A specific embodiment incorporates the components on an integrated circuit chip.

Abstract: The specification describes a process for diffusing a metal into a substrate which may be either a semiconductor material or a dielectric material. The substrate is first coated with a liquid composition comprising organo-metallic solutions of the desired metal and silica. The coated substrate is then heated at an elevated temperature for a period of time sufficient to cause the organic portion of the solution to decompose, thereby leaving a composite film comprising an oxide of the desired metal and SiO.sub.2. Upon further heating, the metal from the metal oxide diffuses into the substrate. The residual composite film may be left in place or removed.

Abstract: A process for suppressing the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 waveguide structures by exposing the structures to a Li.sub.2 O-rich environment at sufficient vapor pressure that Li.sub.2 O diffuses into the structure as a compensation process and a solid-solid surface interaction occurs. In one embodiment of the invention, the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 crystals into which Ti has been diffused is eliminated by annealing the structure in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3. In a second embodiment, the Li.sub.2 O out-diffusion is partially suppressed by annealing the structure in molten LiNO.sub.3. In a third embodiment of the invention, a waveguide structure comprising a Li.sub.2 O-rich guiding layer is formed by annealing LiNbO.sub.3 or LiTaO.sub.3 crystals in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3, which not only suppresses Li.sub.2 O out-diffusion but also promotes Li.sub.2 O in-diffusion into the crystals.