Abstract: A method of operating a computer system is disclosed that is useful in connection with programs that provide the user with messages such as error messages. The error messages are stored in an indexed file, at least some of the messages having token words whose meaning must be provided in order to give complete meaning to the error message. A dictionary list of the definitions for all token words that may be encountered when a command of the program is executed is developed prior to a point in the program where a message is retrieved from the indexed file. If the proper condition is developed to indicate that an error message is necessary, the error message number corresponding to that condition is used to recover the appropriate error message with token words either from the indexed file or from a local header table. The token words are then replaced with definitions from the dictionary list and the error message is delivered to the user.

Abstract: The present invention relates to an apparatus for laser isotope detection and concentration measurement (LIDAM). A test sample containing first and second isotopes of a specific material or compounds formed with the first and second isotopes of the specific material is placed in an optical bridge with a standard sample containing known amounts of the first and second isotopes or compounds of the same. Laser radiation from a first and a second laser source is alternatively focused upon the two samples to produce fluorescence from the isotopes or compounds of the specific material. The laser material of the first laser source and the laser material of the second laser source are either the first and the second isotope respectively or compounds formed with the first and the second isotope respectively. Laser radiation from the first and the second laser source induces fluorescence only from the first and second isotope or compounds of the same in either the test or standard sample.

Abstract: A tracing facility which is useful in a multiprocessing environment on a single processor is disclosed. Tracing statements are encoded within each process, each statement having arguments to indicate its location in the code and a message which is logged when the sybsystem and function corresponding to that tracing statement are selected for debugging. Each process includes a trace library that is called by each trace statement, and the trace library includes a local sync word and a local trace table having a list of the subsystems and functions currently selected for tracing. Each process has access to a global sync word and a global trace table having a list of the processes, subsystems and functions selected for tracing. A change in the trace operation is made by changing a parameter in the global trace table and changing the value of the global sync word to indicate that a change has been made in the global table.

Abstract: The invention provides apparatus comprising at least two beams of coherent radiation directed so as to intersect and form a standing wave pattern having a period .LAMBDA. in an optically responsive medium. The optically responsive medium is a colloidal suspension of dielectric particles in a liquid medium, the dielectric particles and liquid having different indices of refraction, and the diameter of the particles being less than or approximately equal to the period .LAMBDA.. The dielectric particles are arranged into a grating by the electric fields carried by the beams of coherent radiation. In an embodiment of the invention, the dielectric particles are small dielectric spheres. The dielectric particles and the liquid may have approximately equal mass densities. A third beam of light may generate an output beam of light by degenerate four-wave mixing processes incorporating a dielectric grating made by the electric fields carried by the beams of coherent radiation.

Abstract: Metal ellipsoidal particles are deposited on an ordered array of silicon dioxide posts. Each of the particles has dimensions that are less than the wavelength of a fundamental beam to be used in the generation of second harmonic radiation. The rows of particles in the ordered array are spaced at a distance that is less than one-half of the fundamental wavelength and greater than one-half of the second harmonic wavelength.

Abstract: A semiconductor laser is disclosed wherein a grid-like conductive current mask is fabricated between the active region of the laser and one of its electrodes. In one embodiment, the conductive current mask is fabricated in the bottom regions of a corrugated pattern that is created along the length of the semiconductor laser. In a second embodiment, the conductive current mask is totally embedded within a lightly doped buffer layer that is grown proximate to the active region.

Abstract: An electro-optic integrated circuit is disclosed wherein the long electrical connections normally present on a large scale integrated circuit are replaced by an optical waveguide layer. A plurality of epitaxial layers are grown on a single substrate and at least three of the plurality of epitaxial layers are grown with bandgaps that are suitable for optical sources, detectors and waveguiding. These primary layers are separated from each other by a barrier layer having a bandgap greater than either of the adjacent primary layers. Two of the layers adjacent to the substrate are grown to accommodate electrical devices that can be used to couple electrical signals to the optical source layers and to amplify electrical signals provided by the optical detection layer.

Abstract: A process for fabricating a high speed bipolar transistor is described wherein the collector, base and emitter layers are first grown using molecular beam epitaxy (MBE). A mesa etch is performed to isolate a base-emitter region, and a contact layer is grown using MBE over this isolated region to make contact with the thin base layer. The contact layer is selectively etched to expose the emitter layer, and metal is deposited to fabricate emitter, base and collector contacts.

Abstract: Many prior art bistable optical devices require resonant optical cavities and are therefore limited in their operation due to the long lifetimes associated with their high-finesse cavities. A bistable optical device that does not use a resonant cavity is disclosed wherein a nonlinear medium whose index of refraction increases with increased light intensity is arranged to have input and output faces into which and out of which a laser beam having a nonuniform spatial profile can be propagated. A mirror having a predetermined area of reflectivity is positioned with respect to the output face of a nonlinear medium so as to reflect only the light energy that propagates in an area at the output face that is approximately equal to the area which the beam presents at this face when the beam is propagating at a critical power level, that is, when the beam is self-trapped.

Abstract: A ring cavity laser is disclosed wherein a Rhodamine 6G dye stream is used as the gain medium, and a saturable absorber stream is positioned in the ring cavity at a point such that the time difference between pulses arriving at the gain stream is not small compared to the recovery time of the gain medium. The saturable absorber is DODCI dissolved in ethylene glycol passed through a specially constructed nozzle that creates a dye stream having a thickness of about 10 microns in the optical cavity. As a result of this thin saturable absorber, the two counterpropagating pulses that collide in the saturable absorber are caused to interact in a way that results in a decrease of the pulse duration and an equalization of the pulse intensities.

Abstract: In order to prevent drift between the two stable states in the bulk of the liquid crystal material, a specific cell isolation region formed from the same liquid crystal material is required. This cell isolation is provided in one embodiment by a uniformly tilted liquid crystal alignment. The surface of the substrates between which the liquid crystal material is disposed is treated to provide the uniform tilt in regions which surround the bistable volumes of liquid crystal material.

Abstract: 1.

Abstract: Broadband laser gain is obtained in semiconductor materials by pumping an ultra-short laser cavity with picosecond excitation pulses. The broadband laser gain is used to provide picosecond laser radiation energy covering a wide spectrum of frequencies.

Abstract: Optical power is coupled into an optical waveguide system such as an optical fiber with maximum efficiency by a superluminescent light-emitting diode having lateral confinement of the light in the junction plane. The waveguide developed in the light-emitting diode is constructed to have an effective numerical aperture equal to the numerical aperture of the optical waveguide, and the refractive index n, the length L and width D of the waveguide in the diode is constructed such that the parameter nD/2L is much less than the numerical aperture. As a result, the inverted population of electrons within the active region are utilized with maximum efficiency to develop rays that are coupled into, and can be guided by, the optical waveguide system.

Abstract: A method of growing a water insoluble native plasma oxide on an In.sub.0.53 Ga.sub.0.47 As layer of the type that is useful in the fabrication of MOS type devices is disclosed. Oxygen is bubbled through a water chamber in order to introduce water vapor into the growth chamber during the growing process. The InGaAs layer is first sputter etched in the oxygen plasma while a negative potential is applied to the semiconductor structure. The pressure is then increased and the oxides are grown while a positive potential is applied to the semiconductor structure.

Abstract: An atomic or molecular beam detector is disclosed wherein the beam to be detected is coupled through a chopper to form a spatially modulated beam which is then directed at the pressure sensitive surface of a small sensitive microphone. The electrical output signal of this microphone is coupled to a phase-sensitive detector in order to detect the energy that is present in the signal at the frequency corresponding to the chopping rate. In the specific embodiment disclosed, a light beam is also coupled through the chopper in order to develop a second electrical signal which is mixed with the electrical output of the microphone and then coupled through a low pass filter to provide a DC signal when the atomic or molecular beam is present.

Abstract: A dual-wavelength light-emitting diode (10) is disclosed wherein at least two quaternary layers (102 and 104) are epitaxially grown on indium phosphide substrate (100) and a top indium phosphide layer (105) of the opposite conductivity type is grown to establish a junction (121) in the topmost quaternary layer. An isolation channel (106) cuts through the epitaxial layers and divides the device into two separate regions. A dopant is diffused into one of the regions in order to establish a pn junction (122) in the bottom quaternary layer. Independent electrical contacts (107 and 108) bonded to the top indium phosphide layer in each of the regions establish an electrical connection to pn junctions in each of the two separate regions. The device can be effectively heat sinked by mounting the epitaxial layer side of the substrate to a beryllium oxide heat sink (200) onto which gold bonding pads (201 and 202) have been plated.

Abstract: A plurality of semiconductor lasers (431-434) and a photodetector (120) are mounted on a silicon substrate (100) having an integrated circuit (101) fabricated therein. The integrated circuit includes a biasing circuit (405) for establishing a threshold current level that is dependent on the output of the photodetector and a modulator circuit (404) for providing a modulation current that is dependent on the digital values in an input signal. A semiconductor switch (406) selects only one of the plurality of semiconductor lasers for activation by the biasing and modulator circuits. The integrated circuit also includes a circuit (408) that operates the semiconductor switch so as to selectively activate a different one of the plurality of semiconductor lasers in response to either a predetermined output from said photodetector or in response to an external supervisory signal.

Abstract: A high-voltage, high current pulse is applied to a series of two or more conducting strips (101-110) installed in series in a laser cavity (150-151) containing either a buffer gas or a vacuum. The strips are separated by small gaps. When the high-voltage, high-current pulse is applied to the strips, plasmas (141-149) are formed in the gap regions. The plasmas are comprised of ions from the strip material. Once formed, these plasmas expand hemispherically, cool and recombine to provide laser action. The composition of the plasmas depends on the strip material, the electric field in the gaps, the gap size and the background gas type and pressure.

Abstract: A liquid crystal cell having memory is provided by disposing a liquid crystal material having nematic directors between two substrates which are fabricated to contain an array of singular points. The cell may further include means for detaching singularities such as appropriate electrode arrangements.These substrate configurations provide multistable configurations of the director alignments because disclinations must be moved, either through the bulk of the liquid crystal material or on the substrate surfaces to switch between the stable configurations.The switching of the device between stable configurations may be accomplished by the application of electrical fields to the liquid crystal material.The stable configurations may be optically differentiated by the incorporation of pleochroic dyes into the liquid crystal material or by crossed polarizers.