Abstract: A method of compensating for the angular coupling of optical fibers to a tilted facet optoelectronic component involves a precise calculation of the coupling angle with respect to the active layer of the component and with respect to the side walls of the package in which the component is to be mounted. With these angles computed, the tilted facet component is positioned on a carrier at an offset to the perpendicular such that input/output fibers can exit the component package perpendicularly to its sidewalls. The component is secured to the carrier by a solder having a high melting point such that subsequent soldering of parts to the carrier will not affect the component positioning. A localized cooling method then allows the sequential alignment and soldering of one optical fiber at a time to the offset tilted facet component, while previously aligned and soldered optical fibers are held fixed.

Abstract: A technique for measuring the unknown subsurface temperature T of a bulk transparent medium such as sea water by focussing a high intensity pulsed laser beam in a first direction into the water to a predetermined depth D, producing stimulated Brillouin scattering (SBS) in a second direction opposite to the first direction and generating from the SBS stimulated Raman scattering (SRS) in the second direction, analyzing the spectra of the SRS and determining therefrom the temperature T. The depth D is is selected to insure that the entire SBS pulse is in the water.

Abstract: A method for optically coupling multiple single-mode optical fibers to a single packaged optoelectronic array device uses a single graded index lens to magnify the images of the active semi-conductor elements and to expand the spacing between their light beams. These separated magnified light beams then coupled to an associated array of uptapered optical fibers. Simultaneous alignment is possible because the location of the semiconductor array beams can be known with high precision relative to the central beam in the array. A lens with known magnification is first positioned relative to the central beam. Alignment to this central beam automatically aligns other optical fibers held collectively in a fixture engineered with the geometry set by the known magnification of the lens. The coupling of single-mode optical fiber to two-dimensional semiconductor surface arrays utilizes the projected and magnified beams of the array which replicate the precise placement of the array elements.

Abstract: A method of generating high power optical signals in the 1-100 GHz frequency range uses a frequency modulated semiconductor laser and an interferometer. This method is especially useful for microwave carrier frequency optical communications, distribution of microwave frequency local oscillator signals, and the generation of sinusoidal optical modulation at frequencies that cannot be reached by direct modulation in semiconductor lasers or with external module lasers.

Abstract: The I.sub.2 bound exciton in cadmium sulfide (bound to a neutral donor) is a very efficient radiator, providing low switching energy and fast switching times for an ON and OFF optical bistable device, desirable for all-optical signal processing applications. The optical bistable device for light at a given wavelength includes a Fabry-Perot cavity having a pair of opposed mirrored surfaces. A direct bandgap semiconductor, such as CuCl, CdSe, CdS, and GaAs having a bound exciton, is located within the cavity. The cavity is tuned near resonance of the light. The bound exciton has a coefficient of absorption tuned near resonance. A light beam of varying intensity is applied from without the cavity to one of the surfaces. The semiconductor has both an index of refraction and a coefficient of absorption that vary with the magnitude of applied light. Thus, light applied thereto passes through the device either substantially unimpeded or impeded, dependent upon its magnitude.

Abstract: A method of optically coupling an optoelectronic device having a photoactive element to an uptapered single-mode optical fiber which connects said optoelectronic device to an external device includes securing a graded index lens to a substrate carrier within a housing at a distance calculated to provide a known magnification of a light beam emanating from said element, and further includes mechanically positioning and actively aligning the fiber to said magnified light beam to achieve optimal optical coupling to said optoelectronic device. The location of a plurality of reference marks and surfaces are determined such that the photoactive element, the lens and the uptapered end of the single-mode optical fiber may be positioned with respect to these references for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the substrate.

Abstract: A package for an optoelectronic device, such as a laser, having a photo-active element optically coupled to an uptapered single-mode optical fiber which connects said optoelectronic array to an external device includes a housing having a solderable substrate to which the device is secured, a graded index lens also secured to said substrate at a distance calculated to provide a known magnification of light beam emanating from said laser and an uptapered single-mode optical fiber mechanically positioned and actively aligned to said mangified light beam to achieve optimal optical coupling to said optoelectronic device. The package includes a plurality of reference marks and surfaces such that the laser, the lens and the uptapered end of a single-mode optical fiber may be positioned for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the substrate.

Abstract: An integrated optical 2.times.2 changeover switch having four waveguide directional couplers has two wageguide directional couplers cascaded in each path from a port on one side to a port on the other side. Only two electrodes control the switch states of all four couplers. Crosstalk is guided to unused ports of the directional couplers. The extinction ratio is the sum of the extinction ratios of the cascaded couplers in its path. Additional waveguide couplers can be placed in the path of the crosstalk to improve the extinction ratio further.

Abstract: A 1.times.2 integrated optical switch is a monolithic integration of two high-extinction cascaded coupled-waveguide modulators, one of said modulators being a bar-type modulator to provide a straight-through path and the second being a cross-type to provide a cross-over path between input and outputs. The primary and secondary waveguides in each section of the cross-type and the bar-type modulators respectively serve to dissipate unwanted crosstalk. A 2.times.1 integrated optical switch is obtained by reversing the waveguide patterns. The addition of waveguide bends to ends of the secondary waveguides of each modulator results in a bidirectional 1.times.2/2.times.1 integrated optical switch.

Abstract: A quasi-achromatic configuration of two nonreciprocal optical rotators coupled by linear retardation elements based on total internal Fresnel reflection, such that wavelength or temperature effects on the optical rotator elements compensate one another to give quasi-achromatic isolation and/or temperature stability when this optical configuration is incorporated into an optical isolator or circulator. A quasi-achromatic optical isolator through which a light beam within a wavelength range about a nominal wavelength may propagate is made from a sequence of elements having a first plane polarizer accepting said light beam as an input, said light beam then passing through in sequence, a first Faraday rotator, a first wavelength independent linear retardation element, a second Faraday rotator, a second wavelength independent linear retardation element, and said light beam exiting said isolator undiminished in intensity through a second plane polarizer.

Abstract: A multichannel wavelength demultiplexer has two or more cascaded birefringent filter stages for dividing an input signal consisting of a plurality of adjacent channels of optical signals among a number of outputs, each of said filter stages having a transmission function with even symmetry about optical frequencies at the centers of both the longest and the shortest wavelength channels. This symmetry, common to all transmission functions, permits all birefringent filter stages to be constructed from sequences of the same one size crystal element, thereby greatly lowering the cost of construction because solely one size crystal element is fabricated, tested and assembled. A multichannel multiplexer, identical to the above defined demultiplexer, but operated in reverse, is set forth.

Abstract: A junction field effect transistor, specifically a static induction transistor. Prior to metallization a thin layer of germanium is placed over the exposed silicon of the source and gate regions. The germanium is intermixed with the underlying silicon to form a germanium-silicon composite. A rapid thermal anneal is performed to recrystallize the germanium-silicon composite. Alternatively, a single crystal epitaxial layer may be deposited on the silicon. Conventional metallization procedures are employed to produce ohmic source and gate contact members to the germanium-silicon composite or the epitaxial germanium of the source and gate regions. By virtue of the reduced bandgap provided by the presence of the germanium, the contact resistance of the device is reduced.

Abstract: A predictive access-control and routing system for a telecommunications network operating in uncertain environments and capble of handling heterogeneous traffic. The system is a real-time, state-dependent network traffic control system in which the control strategy is a function of both real-time congestion levels and real-time traffic profiles. At specific time epochs, the system, using real-time measurements of source-destination arrival dates and trunk group link occupancies, generates predictions of all network trunk group occupancy levels for the next epoch as a function of routing and access control. It then minimizes a projected cost function, such as blocking, to generate a traffic control policy to be implemented during the next time interval.

Abstract: A power amplifier circuit utilizes vertical power transistors, such as static induction transistors, field effect transistors, or bipolar junction transistors, in a configuration where an ungrounded terminal serves as a common node while a separate reference terminal is connected directly to ground. A transformer of appropriate bandwidth couples an rf input signal to the input terminals of the transistor such that the input terminals are floating relative to ground. The novel amplifier circuit establishes separate electrical paths between the common terminal and the input circuit and between the common terminal and the output circuit. Thus, negative feedback is not present in the common lead, thereby improving gain, power output, and efficiency. Moreover, the circuit, in either a BJT, FET, or SIT configuration, can be fabricated on thinned semiconductor chips to form a transistor package in which the chips are bonded directly to the package heatsink.

Abstract: A broadband switching array for equalizing the delay experienced by input signals as they propagate through their respective swtiching hpaths, and for providing output signals having uniform logical polarities. A cascaded set of delay means is connected to each of the input ports of the array in accordance with the amount of additional delay that is needed to accomplish equalization. Likewise, a cascaded set of inverter means is connected to each ouput port so that each switching path performs a common number of inversion operations, thereby allowing the output signals to have the same logical polarity.

Abstract: Glass compositions for high efficiency erbium.sup.3+ -doped optical fiber lasers, amplifiers and superluminescent sources are optimized for pumping by high power solid state lasers in the vicinity of 800 nm to provide amplified signals in wavelengths between 1.5 and 1.7 microns, a principal telecommunications window. A number of suitable host glasses for doping with erbium 3+ are identified wherein the excited state absorption/ground state absorption intensity ratio calculated at 800 nm is 1.00 or less.

Abstract: An optical parallel-to-serial converter constructed from at least two optical shift registers coupled in cascade by an optical two-to-one combiner. The input port of the first optical shift register serves as one input to the parallel-to-serial converter, an extra optical combiner optically coupled to the last of said optical shift registers serves as one input port, while the optical combiners coupling said optical shift registers serve as the other input ports receiving parallel optical pulses. The output port of the last of said cascaded optical shift registers serves as the output port of the parallel-to-serial converter. The shift registers are controlled by two clocks, operating at the same rate, but each out of phase with the other, providing control signals to shift and output said optical pulses serially from said shift registers to effect a parallel-to-serial conversion.

Abstract: A package for an optoelectronic array device having an array of n active elements optically coupled to an array of n single-mode optical fibers which connect said optoelectronic array to an external device includes a housing having a solderable substrate to which the array device is secured, a graded index lens also secured to said array at a distance calculated to provide a known magnification of light beams emanating from said array and n uptapered single-mode optical fibers actively aligned to said magnified light beams to achieve optimal optical coupling to said optoelectronic array. The package optionally includes a multifiber holder having precisely calculated spacing based on the spacing of said active elements which are usually semiconductor lasers and the magnification of said lens. For a two-dimensional surface array, the package includes a mandrel to position the uptapered optical fibers.

Abstract: A true n-by-n optical crosspoint matrix switch has n optical fiber outputs each carrying the same light that entered the switch at one of n fiber inputs, maintaining the full optical spectral characteristics although the polarization states may be modified. A mounting plate on a patch panel has an n-by-n array of connection adapters in n rows and no columns. An electromechanical positioning mechanism is utilized to position n input fibers along one row to any of n adapter positions each in a different column on a first side of said plate, and n output fibers along one column to any one of n adapter positions, each in a different row on a second side of said plate. Any input fiber can be connected to any output fiber and none of the adapters are shared by more than one input or one output connector.

Abstract: An expanded beam connector for optical fibers uses a transparent lensing device having integral alignment capability, that of a simplified design that facilitates its molding with high precision from optical plastic or glass.