Abstract: In this invention, there is disclosed a new photodiode which comprises a semimetal/semiconductor junction. Distortion of the bands associated with this type of junction result in current flow when an electron hole pair is formed by, for example, a photon impinging upon the junction. The photodiode operates in the photovoltaic mode. However, rather than relying on impurity doping to fabricate a p-n junction, the semimetallic nature of HgTe and its large conduction band offsets with Hg.sub.1-x Cd.sub.x Te are used to create a rectifying Schottky like structure.

Abstract: In accordance with the principles of the present invention, a connector for coupling a coaxial transmission line to a strip transmission line comprises a length of transmission line having an inner conductor having a longitudinal axis, an annular ring of dielectric material disposed around the inner conductor and an outer conductor. The length of transmission line at one end, is coupled to a coaxial transmission line connector. The other end of the transmission line is mounted to a printed wiring board which supports a controlled impedance strip transmission line and the inner conductor, which projects beyond the dielectric material immediately adjacent the strip transmission line, is electrically coupled to the strip transmission line. The ground plane, located either on the same side or the obverse side of the printed wiring board is coupled to the outer conducting member of the length of transmission line either directly or via a conductive trace.

Abstract: The present invention relates to a technique for interfacing a plurality of remote terminals, as, for example, Craft Access Terminals (CATs), directly to a central database in a system, such as, for example, a Craft Access System, without interfacing with an intermediate center such as, for example, a centralized Repair Service Bureau and its personnel. An Applications Processor Microcomputer (APM) module includes a General Data Transport (GDT) to provide a powerful microprocessing environment and multiple data communication interfaces, and an Applications Interface Module (AIM) to provide the appropriate signal interface with the database system, the GDT, and the remote terminals.

Abstract: The invention is an optical isolator. In one embodiment the optical isolator comprises two linear polarizers, one at the input of the isolator and the other at the output. Positioned between the input and the output linear polarizer is a gyrotropic medium located within a resonant cavity such as a Fabry-Perot cavity. Interposed between the linear polarizer at the input of the isolator and the resonant cavity is a first polarization conversion means for converting received plane polarized optical energy from said linear polarizer to circularly polarized optical energy and interposed between the resonant cavity and the linear polarizer at the output of the isolator is a second polarization conversion means for converting received circular polarized optical energy from said resonant cavity to plane polarized optical energy. In an embodiment, the resonant cavity comprising the gyrotropic medium becomes the filtering medium to block reflected optical radiation.

Abstract: With this invention, collisions of optical packets in local area networks are avoided. Briefly, each branch of a local area network topology, such as a star, a ring or a bus is provided with an optical path having two substantially parallel optical fibers which can be selectively configured to form either a direct straight through path or a loop-back path. Prior to advancing a packet to the next occurring branch, a test is made to determine if it is occupied. If it is not occupied, the packet is advanced along one of the opitcal fibers of the optical path. If it is occupied, then the two optical fibers are rapidly configured to form a loop-back path and the packet travels around the loop-back path, again and again as required until the danger of a collison with a preceding packet no longer exists.

Abstract: This invention is directed toward reducing substantially the loss incurred when two optical fibers of different mode diameters are coupled together. In this invention, the coupling of one fiber to that of another where the fibers are of different mode diameters is not with a tapered fusion, core-to-core splice, but with an evanescent field fiber coupler. Briefly, to achieve amplification of a weak optical signal, an amplifying fiber is inserted into the system at one or a plurality of locations. More specifically, at a desired location, the transmission fiber is severed to provide two sections and the severed sections are transversely coupled to the amplifying fiber. The weak signal from the first section of the transmission fiber is coupled into the amplifying fiber via a first evanescent field type of fiber coupler; and the amplified signal is coupled from the amplifying fiber to the second section of the transmission fiber via a second evanescent field type of fiber coupler.

Abstract: This invention is a mobile, short range, high data rate, high availability atmospheric optical communication link which can be used to temporarily bridge a break in an optical fiber network. Briefly, the invention comprises two transceivers, one at each end of a break, to bridge a severed optical fiber via an atmospheric optical transmission path which can extend for a distance of roughly 5 miles. A special light source is not required. The light transmitted through the atmosphere is the low power light emitted from the end of an optical fiber and generated by an optical regenerator normally used to generate light only for transmission through an optical fiber. The light is first expanded and collimated for atmospheric transmission and then transmitted to a receiver. At the receiver, the diameter of the received beam is optically reduced by focusing it onto the end of an optical fiber for coupling the light into the fiber.

Abstract: Briefly, in the invention a photodetector and an injection laser are monolithically integrated on the same semiconductor chip. The laser and photodetector are positioned side-by-side and the laser mirrors can be formed by cleaving. In operation, a portion of the electromagnetic energy carried in the evanescent tail of the optical mode is detected by the photodetector for monitoring the average output power of the laser. Current confinement and lateral index guiding can be provided by Fe or Ti doped semi-insulating layers of InP. The side-by-side arrangement enables the photodetector to monitor the output power of the laser without degrading the output power.

Abstract: Briefly, in this invention, the output optical power of an optical amplifier is determined by detecting and measuring the electrical signal induced on the bias lead of the optical amplifier when an optical data stream with additional amplitude modulation passes through the optical amplifier. This additional amplitude modulation can consist of a base band signal, a pilot tone and/or a sub-carrier which is amplitude modulated, frequency modulated or phase modulated. The modulation depth and bandwidth of the additional amplitude modulation should be kept small enough that the data stream is not excessively affected. The induced electrical signal provides a measurement of the optical power at the output facet of the optical amplifier. Control of the output power of the optical amplifier is effected by controlling the bias current applied to the bias lead of the optical amplifier.

Abstract: The invention, which can be used with AT&T SKYNET.RTM. digital satellite communications service allows a conference director to control a teleconference between several conference rooms. In this invention there are two transmitting channels, one being identified as a broadcast channel and the other is identified as an auxiliary channel. The conference director can assign the broadcast channel to any room and the auxiliary channel to any other room. The video signal on the broadcast channel is sent to a first satellite dish for frequency division multiple access transmission via a satellite to all of the other conference rooms. The video signal on the auxiliary channel is sent to a second satellite dish for frequency division multiple access transmission via the satellite to the conference room from which the broadcast channel originates.

Abstract: To prevent an interruption of service due to a break in an optical fiber, the information being transmitted is normally sent along two diversely routed lightwave paths using two complete transmitter sections, one for each path. Briefly, in this invention a single optical transmitter which can be an optical modulator such as a lithium niolate switch is used to impress a digital signal on a CW optical beam to obtain two digital optical outputs. One output is normally used as the modulated line signal for one of two diversely routed paths. The other output, which is the complement of the modulated signal, is used as the modulated line signal for the other of the two diversely routed paths. When the complement of the signal is detected, complementation can be performed to retrieve the original bit pattern. The advantages over the prior art are significant. For example, only one tansmitter is required. The laser is on continuously and, therefore, there is no chirp.

Abstract: This invention is an optical memory device in which data is written, stored and read out in optical form without any conversion to electronics. The functions performed such as readout, reset and the like can be via electronic means, optical means, or a combination of both. The inherent bistability/hysteresis which is required for the memory function is obtained with a laser structure which includes a saturable absorber and, as a portion of the cavity, a waveguide.

Abstract: A female pin connector is disclosed which inhibits damaging levels of an electrostatic discharge from entering the unmated pin connector. The female pin connector supports a conductive barrier member at the mating end of the pin contacts. The conductive barrier member, which can be in the form of a conductive sheet, strip, wire, printed circuit or the like is located outward from and encompasses the mating end of the pin contacts. The conductive barrier member is adapted to be coupled to a member which can receive and safely dissipate the electrostatic discharge.

Abstract: A star coupler for a single-mode-fiber optical local area network which reduces the amount of fiber required by a factor of two and diminishes the number of components by one-half. This savings in fiber and components is effected by "reflecting" signals which appear at various locations of the network back toward the input ports. The arrangement forms a broadcast-type of local area network where a message transmitted by any user can be received by all users.

Abstract: An ion energy filter of the type useful in connection with secondary ion mass spectrometry is disclosed. The filter is composed of a stack of 20 thin metal plates, each plate being insulated from the others and having a centrally located hole with a unique radius. A metallic hemisphere is mounted on a base plate, and the 20 thin metal plates are attached to the base plate such that the plate with the smallest central hole is adjacent to the base plate and the radii of the holes in subsequent plates increase with increasing distance from the base plate. The relative potential of each plate is determined by a series string of 20 resistors with each plate being connected to a different junction in the series string. The radii of the centrally located holes are selected such that the voltage on each plate is inversely proportional to the radius of its centrally located hole.