Abstract: A method and apparatus for substantially reducing OBI on optical networks in which a number of source lasers operate simultaneously and the output from the lasers is subsequently combined in the network. The method involves operating the laser in burst mode such that the laser is operational only during transmission periods.

Abstract: A novel quantum cascade (QC) laser comprises a multiplicity of identical repeat units, with each repeat unit comprising an active region and an injector region. The injector region comprises quantum wells and barriers, selected to facilitate, under appropriate bias, resonant carrier transport from a lower energy level of a given active region to an upper energy level of an adjacent downstream active region. Carrier transition from the upper energy level to a lower energy level of an active region results in emission of infrared radiation. The laser is advantageously used in, e.g., a measurement system for detection of trace compounds in air.

Abstract: A noise-computation method that determines the noise power cross-spectral density matrix of an electronic circuit or system in the form of a closed form rational expression. More specifically, the method provides a matrix-Pade approximation of the noise power cross-spectral density matrix using a numerically robust and efficient block Lanczos-type method.

Abstract: The specification describes source/drain contact material that is compatible with organic semiconductors in thin film transistor integrated circuits. The contact material is nickel/gold wherein the nickel is plated as Ni--P on a base conductor, preferably TiN.sub.x, by electroless plating, and the gold overlay is deposited by displacement plating. It was found, unexpectedly, that forming Ni/Au contacts in this way extends the lifetime of TFT devices substantially.

Abstract: A battery diagnostic method for monitoring the status of a battery in an electrical system and continuously providing a relatively accurate prediction of battery condition and performance, more particularly, a self-adjusting method for providing the best possible prediction of a battery's reserve time before, during, and after a battery discharge. The method of the present invention utilizes different prediction methods depending on what state the electrical system is in; that is, before, during or after a battery discharge. By determining what state the system is in, the most effective prediction method can be utilized to provide an accurate battery reserve time. By providing a relatively accurate continuous reserve time prediction, the method helps prevent a complete loss of power in an electrical system relying on a battery to supply the system's electrical power.

Abstract: A method and apparatus are disclosed for testing individual laser chips located on a laser bar containing a plurality of chips. Laser bars are transported widthwise on a moving plastic film sheet, which is passed over an elongated pedestal which is aligned with the film sheet. The pedestal has a width which is less than the length of a laser bar, so that the unsupported portion of the plastic film under the ends of the laser bars may be drawn downward and away from the bar. This provides access to the metalized underside of the bar, which serves as a common N-contact for all of the laser chips on the bar. A probe is placed in contact with the undersurface of the bar, and at least one additional probe is placed in contact with a P-contact on one of the laser devices. A chip activation signal is applied between the two probes, and a sensor detects whether or not the chip being probed emits radiation. Failure to emit radiation or to emit radiation in an expected manner is indicative of a bad chip.

Abstract: A dispersion compensating chirped optical fiber Bragg grating according to our invention is formed in polarization maintaining (PM) fiber having birefringence of at least 10.sup.-6, preferably 10.sup.-5 or more. Use of the PM fiber makes possible substantial cancellation of the polarization mode dispersion that typically is unavoidably present in chirped Bragg gratings for dispersion compensation.

Abstract: An apparatus for drying cable, in accordance with the present invention includes a trench formed longitudinally on a plate for receiving a cable whereby a plurality of openings formed in the trench permit fluid communication therethrough such that water present on the cable is removed through the openings by evacuation. A water separator is coupled to the bottom portion for receiving the evacuated water and separating out the water by gravity.

Abstract: A voice messaging system enables a callee to specify a retention time for retaining a stored voice message from a caller. The system then automatically deletes the stored voice message after the expiration of the retention time. In one embodiment, the caller is able to specify one retention time when the message is first recorded, and the callee can change that retention time when the message is retrieved. If the message is not retrieved by the callee before the caller-specified retention time expires, the system will automatically delete the message. In one embodiment, a callee can also assign a retention time to an outgoing voice message for playback to subsequent callers. The present invention improves the operations of a voice messaging system with limited memory resources, by reducing the chances that the system's memory will become filled with old messages which would leave the system unable to store new messages from callers.

Abstract: A high voltage integrated driver circuit having a control stage and a driver stage. The control stage receives a low voltage signal having a predetermined voltage swing, and produces first and second stepped-up output signals having the predetermined voltage swing. A driver stage having an upper section and a lower section is connected to the control stage such that the upper section receives the first stepped-up output signal and the second section receives the second stepped-up output signal. Each driver section outputs, from a respective output terminal, and output voltage signal such that the voltage range across the output terminals is larger than the predetermined voltage swing of the low voltage signal.

Abstract: Low-noise, bidirectional communications in a fiber optic cable is achieved by coupling a first end of the cable to an optical power source having an inherently broad spectral width. A second end of the cable is coupled to an optical detector having a detector bandwidth, such that the bandwidth of the optical power source is greater than the detector bandwidth. When the bandwidth of the optical power source is large compared to the bandwidth of the detector, the beat frequencies resulting from coherent Rayleigh noise fall outside the bandwidth of the detector and are not detected.

Abstract: An optical probe is positioned between a pair of connectors positioned substantially adjacent to each other so as to read identifying markings on the face or surface of one of the connectors. The optical probe includes a probe head and an illumination device for projecting light substantially parallel to the face of one of the connectors, i.e., a surface being imaged. The illumination device includes a bifurcated fiber optic cable and a pair of prisms positioned so as to illuminate the surface being imaged from opposite directions. A spectral image representative of light scattered by laser etchings on the surface, or light reflected or absorbed by other markings on the surface is projected by a cylindrical mirror through the path of the light from the illumination device to a camera. The camera displays the image of the surface being imaged on a monitor. The probe head is substantially flat and thin so as to fit between the connectors without damaging the connectors.

Abstract: A system for providing segmented control of a single, homogeneous routing structure, such as a switch fabric, includes application control elements that are each responsive to embedded signal status information for each of the input signals to the switch fabric. Within each of the application control elements, a configurable arrangement of selectors and control logic is used to provide domain segmented control of each of the separate switching functions for a particular application. Each application control element performs an application specific address resolution function to resolve a single address of one of the input signals based on the embedded signal status of each of the input signals. This single address is provided to the switch fabric so that the corresponding input signal can be selected at the switch fabric output.

Abstract: A clock generator having a ring structure and a chain structure. The ring structure is formed of an even number of serially connected distributed oscillator elements, and the chain structure is formed of an even number of serially connected distributed oscillator elements. The chain structure is coupled across an odd number of oscillator elements in the ring structure. The ring structure and chain structure, when connected together, generate a clock signal that can be extracted from any of the distributed of oscillator elements.

Abstract: In a method of incorporating BIST (built-in self test) circuitry in an integrated circuit, at least one metal layer is arranged to relieve stress in the substrate under bond pads from wire attachment to these pads. By providing at least one stress relieving metal layer, which can be incorporated into electrical paths of the bond pads and related circuitry, BIST circuitry can be provided, at least partly, in the conventionally non-active semiconductive portion of the substrate under the bond pad. The method allows BIST circuitry to occupy conventionally non-active areas under the bond pads wherein leakage current from stress cracks in dielectric layers under the bond pads can be redirected to a metal layer.

Abstract: A process for device fabrication is disclosed in which two substrates having different crystal lattices are bound together. In the process the substrate surfaces are thoroughly cleaned and placed in physical contact with each other. The duration of the contact and the pressure of the contact are selected to facilitate a bond between the two substrate surfaces that results from attractive Van der Waals' forces between the two surfaces. The bonded substrates are heated to a moderate temperature to effect escape of gases which may be entrapped by the substrates. The bulk of one of the substrates is then typically removed. The substrates can be heated again to a moderate temperature to effect removal of any gases remaining entrapped on the substrates. Thereafter, the bonded surfaces are heated to a high temperature to effect a permanent bond.

Abstract: A battery recharging circuit for a valve regulated lead-acid battery having a plurality of cells, each cell including a positive electrode, a negative electrode, a DC voltage source for generating a voltage applied to the positive and negative battery electrodes, and a reference electrode includes a regenerating voltage source for selectively applying a regenerating voltage between the reference electrode and one of the battery electrodes for regenerating the reference electrode, and a reference voltage source for generating a reference voltage. The circuit further includes circuitry for measuring the voltage level between the reference electrode and a battery electrode after removal of the regenerating voltage from the reference electrode. Circuitry compares the measured voltage level to the reference voltage to generate an error correction signal.

Abstract: An apparatus is provided for multiplexing optical signals in an optical network. In accordance with one aspect of the invention, the apparatus includes a plurality of input fibers disposed to receive a plurality of optical input signals. Each optical input signal is defined by a wavelength. A first converter is disposed in series with each of the plurality of input fibers, and is configured to convert each optical input signal into an electrical input signal in a manner such that each electrical input signal is defined by a frequency that corresponds to the wavelength of the optical input signal. A second converter is disposed in series the first converter, and is configured to convert the electrical input signal into a plurality of optical signals of differing wavelengths at an output.

Abstract: A variable optical attenuator includes a lens, first and second optical waveguides, and a semiconductor micro-electro-mechanical device positioned on a side of the lens opposite the first and second optical waveguides. The semiconductor micro-electro-mechanical device may be, for example, a digital micromirror device or a silicon micro-electro-mechanical system. The device has a reflecting surface. The reflecting surface has a normal position in which light from the first waveguide reflects off of the reflecting surface and passes through the lens into the second waveguide. The reflecting surface has a plurality of respectively different attenuating positions in which light from the first waveguide reflects off of the reflecting surface and passes through the lens, but an amount of light entering the second optical waveguide is attenuated by respectively different amounts corresponding to the respectively different positions. By pivoting the reflecting surface about 0.

Abstract: Speech recognition in which the log probabilities of the null and alternative hypothesis are computed for an input speech sample by comparison with specific stored speech vocabularies/grammars and with general speech characteristics. The difference in probabilities is normalized by the magnitude of the null hypothesis to derive a likelihood factor which is compared with a rejection threshold that is utterance-length dependent. Advantageously, a high-order polynomial representation of the rejection threshold length dependency may be simplified by a series of piece-wise constants which are stored as rejection thresholds to be selected in accordance with the length of the input speech sample.