Abstract: An optical device comprising an optical waveguide having a varying refractive index has low radiation loss. The waveguide may be either curved or tapered.

Abstract: High-power, single transverse mode laser operation is achieved in an extended-cavity structure by combining a semiconductor gain medium having a large optical cavity together with a length of single mode optical fiber between first and second reflector surfaces. The first reflector surface is formed on an end facet of the semiconductor gain medium; the second reflector surface is formed on an end of the optical fiber. Output power is efficiently coupled from the fiber end of the extended-cavity laser to a standard transmission medium.

Abstract: Low-loss coupling between a local feed connection or node, and a multi-mode optical fiber bus is provided by reflective insertion of a relatively small number of modes into the bus fiber. Essentially all input power available at the node is thus inserted into the bus, while but a small portion of power is extracted from the bus.

Abstract: Prior art techniques for velocity matching the optical wave and the modulating electrical wave in traveling wave, electrooptic devices includes the use of phase reversals and intermittent interaction. This results in a device whose frequency response includes a single peak. It has been discovered that by reducing the length of the interaction intervals between the electrical and optical systems, a multiplicity of harmonically related frequency peaks can be obtained. Furthermore, by combining the phase reversal and intermittent interaction techniques in a common device, the available bandwidth can be doubled.

Abstract: By introducing an asymmetry in the effective refractive index profile of a waveguide, wave energy can be extracted from the waveguide by radiation at wavelengths greater than a critical wavelength, where the latter is a function of the effective index distribution. This technique is employed to develop a variety of optical wavelength filters.

Abstract: Because the refractive index of materials varies as a function of frequency, velocity matching of the electrical modulating signal and the optical signal in an optical velocity matched gate requires a special design of the electrical circuit. This requirement is avoided in a velocity mismatched gate simply by shaping the electrical signal wavepath so that interaction of the standing electrical wave with the optical wavepath occurs only along selected regions of the electrical signal wavepath. The net effect is to produce the equivalent of a velocity match.

Abstract: The coupling between a pair of coupled wavepaths (11, 12) is modulated by means of a biasing wave travelling in synchronism with the signal in the coupled wavepaths. In particular, by limiting the coupling to a small interval about the zero crossover point of the biasing signal, subpicosecond pulses can be generated by means of a simple sine wave biasing signal. Such a velocity matched gate can be employed as a pulse generator; a modulator; a multiplexer/demultiplexer; and pulse shape analyzer.

Abstract: A graded index, multimode optical waveguide. The waveguide is characterized by a graded profile region, followed by an abrupt drop in index, then a region of constant index. At predetermined intervals, the fiber is modified to have a conventional graded index profile to suppress unwanted modes propagating along the guide.

Abstract: Integrated optics directional coupler modulator/switches are improved by the disclosed configurations for switching optical modes of both polarizations at once. In one configuration a pair of parallel optical waveguides are provided having material presenting first and second wavenumbers .beta. for the TE and TM modes. Two independently tunable control signals are applied to an electrode assembly arranged so that each wavenumber is substantially tunable relative to the other thereby permitting substantially complete switching of both of the modes. In an exemplary embodiment, the material is lithium niobate or lithium tantalate with its c-axis perpendicular to the waveguides and oriented between 15 and 75 degrees, suitably at 45 degrees, to the substrate plane. Pairs and triplets of electrodes are used as appropriate to provide vertical and horizontal electric field components so as to independently tune the waveguide wavenumbers and coupling.

Abstract: This application discloses an arrangement of optical fibers in a group that is particularly adapted for simple and efficient splicing. The fiber group comprises a plurality of optical fibers secured to a ribbonlike tape. In one embodiment the fibers are uniformly spaced from each other in the transverse direction, and mounted therealong in a manner to permit transverse displacement of the fiber axes when forced. A plurality of such fiber groups are disposed within a common enclosure to form a fiber cable.