Abstract: An infrared data repeater adapted for providing communication of infrared signals across an infrared transmission barrier comprises a pair of relay units mounted at opposite ends of a housing. The housing may be mounted in the wall of a building. Arrays of receiver and transmitter elements of the relay units are configured to provide communication over substantial solid angles. The relay units may be selectively directionally orientated. The elements define different effective pre-established solid angles of reception and transmission. The elements are arranged so that there is an inverse relationship between the solid angle and the distance between the element and a corresponding infrared receiver or transmitter.

Abstract: An analog coupling device for coupling a telephone to a telephone network circuit while maintaining isolation of the two circuits has an optical emitting element and an optical receiving element in the network circuit. The telephone circuit includes an optical receiving element optically coupled with the network circuit optical emitting element. The telephone circuit optical receiving element has a reversed biased pn junction. The telephone circuit further includes an optical emitting element which is optically coupled with the network optical receiving element.

Abstract: The method and associated system for providing increased information carrying capacity in optical fiber communication through frequency-division-multiplexing, comprising the steps of generating a reference optical beam, generating a plurality of closely spaced optical carriers having frequencies which are coherently related to the reference frequency of the reference optical beam and which are capable of drifting with the reference frequency while maintaining coherence therewith, and combining the plurality of closely spaced optical carriers to provide a multiplexed optical output beam.

Abstract: A digital data transmission system by modulating a coherent light wave is provided using modulation of the MSFK type with N frequencies for modulating the light wave. The transmitter comprises a coherent light source, a modulator, an output optical means and an MSFK modulation signal generator. The receiver comprises an input optical means, local light wave source and a heterodyne mixer for creating an electric signal of intermediate frequency. A demodulation and detection circuit comprises filtering means for separately selecting the N frequencies before detection. A processing cirucit puts the data back into its initial form. A circuit for compensating for the drift of the light sources is used for preserving lock on to the intermediate frequency.

Abstract: A heterodyne laser detection system includes a local oscillator laser, an infrared light detector positioned to receive light transmitted through a receiving window and also from the local oscillator laser and to generate heterodyne signals in response thereto. An oscillator controller repeatedly sweeps the frequency of the local oscillator laser to ensure that the laser signal being sought generates heterodyne signals within the limited passband of an intermediate frequency amplifier. Upon detecting heterodyne signals amplified by the intermediate frequency amplifier above a defined threshold, the oscillator control switches to control the local oscillator laser to track the detected laser signal such that the heterodyne signals remain within the passband of the intermediate frequency amplifier.

Abstract: A high-speed light emitting diode driver circuit for optical communication systems, in which an impedance circuit is provided between the collector and emitter of a drive transistor, and another impedance circuit is provided on the emitter side. The light emitting diode is connected to the collector side of the drive transistor. The light emitting diode is driven by an input pulse signal applied to the base of the drive transistor.

Abstract: A method of mixing light from a signal source with light from a local oscillator for heterodyne or homodyne detection using differential detection techniques is described. In the method and apparatus of the invention, incoming light is matched to the polarization of the local oscillator no matter what the polarization of the incoming light is. A sequence of three polarization beamsplitters is utilized to achieve this match. The local oscillator signal and the incoming signal are incident on separate faces of a first polarization beamsplitter. Each is divided into two beams by that beamsplitter and paired with the orthogonally polarized component of the other, each signal/local oscillator pair exiting from one exit face of the first polarization beamsplitter. The second polarization beamsplitter resolves one of these pairs into sum and difference pairs of matched polarization which interfere and are detected by square law detectors, forming currents which are subtracted in a differential amplifier.

Abstract: The present invention relates to coherent optical heterodyning receivers which mix a received optical signal, including an arbitrary polarization state, and a local oscillator signal, including a fixed polarization state, while providing a performance which is independent of the polarization direction of a received signal. In one receiver version, the received signal is heterodyned using only a portion of the local oscillator signal, while in a second receiver version, the entire local oscillator signal is used. The combined polarized signals are split in a polarizing beam splitter between the two orthogonal polarization axes for propagation in separate branches. Each branch includes a photodetector and means for processing the resulting photodetector output signal to retrieve the modulation information from the processed signal. The sum of the two demodulated signals from the two branches provides a baseband signal independent of the polarization state of the received optical signal.

Abstract: The present invention relates to an optical heterodyne mixer providing image-frequency rejection which (a) detects a desired signal at frequency f.sub.L.O. .+-.f.sub.IF while rejecting interference from any signal at the image frequency f.sub.L.O. .-+.f.sub.IF, and (b) provides performance which is insensitive to fluctuations in the optical dimensions of the circuit. More particularly, the mixer receives both a local oscillator input signal and a received input signal comprising one or more optical signals, one of the input signals being linearly polarized and the other being circularly polarized. The two signals are merged by an optical device and transmitted to a polarizing beam splitter which has its polarization axes oriented at 45 degrees to the polarization direction of the linearly polarized signal. Each of the two beams from the polarizing beam splitter is detected by a separate photodetector and the resulting two currents from the two photodetectors are added by means of a 3 dB 90 degree IF coupler.

Abstract: In an optical network system comprising a plurality of communication stations (21) and a star coupler (22) common to the stations, a collision test signal is produced from a generator (50) included in a transmitter section (31) of each station to be sent to the star coupler prior to transmission of a data sequence and is directly returned from the star coupler to a receiver section (32) thereof. The receiver section comprises a detector (51) for monitoring the collision test signal to detect occurrence of collision. The detector makes the transmitter section intercept the data sequence on occurrence of the collision. Preferably, the collision test signal is encoded by an encoder (37) in the transmitter section to be combined with a snychronizing signal and is decoded by a decoder (42) in the receiver section.

Abstract: In an asychronously operating optical data bus:(a) data collisions are detected via two analog comparators by amplitude evaluation if the input optical power fluctuations at the site of a receiver as a function of all transmitters do not exceed approximately 3 dB; or(b) at first only one or more transmitting subscribers detect collisions and communicate this to other subscribers by one or more JAM signals; or(c) each subscriber interrogates, during the time which corresponds to its bus turn-around time, whether in its receiver, data signals are arriving from the bus.

Abstract: An optical transmission system is disclosed wherein a multiplexed analog signal is supplied to a laser diode to modulate the intensity of a long-wavelength laser beam. A single mode optical fiber transmission medium has a first inclined end face at a proximal end and a second inclined end face at a distal end. The laser beam is coupled to the proximal end of the transmission medium by a coupling means including a single mode optical fiber connecting medium having one end connected to the laser diode and an opposite end having a third inclined end face complementary to the first inclined end face and a coupler for coupling the first and third inclined end faces in abutment relation.

Abstract: In an optical communication set a local transmission equipment, in which a call switch is previously pressed, becomes a master side. The local transmission equipment at the other side automatically becomes a slave side in response to a burst digital signal transmitted from the master side. The master side equipment supervises the transmitting signal and the receiving signal, adds a signal for deciding a sync state in the transmitting signal, and transmits it to the slave side equipment. The slave side equipment detects the sync signal, controls the timing of its transmitting signal, and transmits the signal to the master side equipment, thereby making a communication state of two-way time division optical communication having a predetermined sync relationship. When the transmission call of either side is made, the relationship between the master side and the slave side is established.

Abstract: An AGC circuit including a precision voltage clamp and method by which a receiver output voltage may be referenced to virtualy any level desired. The circuit and method of the present invention provide an extremely precise AGC and fast clamp ideal for use in RGB data transmission in a fiber optic receiver.

Abstract: An apparatus and method for improving VLSI and VHSIC system data transmission relies on a plurality of optoelectronic switches actuated by pulses from at least one light source, a laser. Differing lengths of optical fibers couple the pulsed light from the laser at different times to create a sequence of actuation light pulses for the plurality of optoelectronic switches each time the light source is pulsed. Thus the information appearing at a plurality of parallel data nodes is converted to serial form at an output bonding pad on the chip. Optionally, a similar pulsing of electrooptic switches coupled to an input bonding pad converts serial data to parallel form. Faster input and output switching times are provided, reliability and complexity are reduced, particularly as compared to off-chip coupling arrangements, and power consumption and dissipation are reduced.

Abstract: A wavelength-division multiplex component for an optical broadband ISDN network with monomode transmission fibers is an uncomplicated component for bi-directional optical wavelength-divison multiplex transmission composed of a rod lens, a wavelength selective filter planarly applied to a front surface of the rod lens, and a plug member surrounding the rod lens and the filter. Monomode and multimode light waveguides are held in the plug member and are butt-coupled to a back surface of the rod lens. The monomode light waveguide fiber is preferably aligned to the optical axis of the rod lens and the front end face of the rod lens is preferably inclined slightly relative to the optical axis so that the multimode light waveguide, which extends parallel to the monomode light waveguide, can be offset laterally therefrom.

Abstract: A multiplexer device includes a plurality of optical fibers. One of the end faces of each of the fibers is arranged in a common plane. The fibers include a first optical fiber for conducting several light signals of different wavelengths and at least two second optical fibers, each of which conduct a light signal in a single waveband. The device also includes a wavelength-selective element (33) and a lens system (51, 53) which is arranged between the wavelength-selective element and the common plane. In order to minimize the number of components of the device and to facilitate adjustment during assembly, the lens system is formed by a plane parallel, transparent plate (51) which bears against the end faces (9, 11) of the optical fibres as well as by a lens (53) having the shape of a flattened sphere whose plane surface rests on the plate.

Abstract: Integrated optic devices incorporating echelon gratings suitable for use in performing multi/demultiplexing functions in optical communications systems. The echelon gratings can be either reflection or transmissive types and are conveniently formed using conventional photolithographic techniques.

Abstract: A synchronizer (10) for frequency division multiple access signals (FDMA) permits synchronization on board a communications satellite without feedback to a multitude of ground-based user stations. Fourier transform processors (12, 13) sample the FDMA signal at half the FDMA baud rate and provide a series of pulses. Frequency translators (14, 15) frequency translate each pulse to frequency align across channels the content of one respective complete symbol segment to be isolated by bandpass filters (16, 17). A demodulator 18 provides a synchronized time division multiplexed output. Two channels alternately sample the FDMA signal to obtain full decoding.A synchronization processor (20) is provided to ensure that the pulses undergo appropriate frequency translations. The synchronization processor detects TDM pulse amplitudes (at 22) and compares them (at 24) to obtain a discriminate which sets a translation frequency (at 26) for each FDMA channel.

Abstract: An optical communications system includes an optical bus and a plurality of terminal devices coupled to the bus and a reference signal generator for propagating a reference signal through the bus for use by all terminal devices in selecting one of a predetermined number of frequency distinct communications channels. The reference signal is frequency swept in a recurring manner between two fixed frequencies and is introduced onto the system bus, along with a system synchronization signal, for propagation to bus tap resonators associated with the terminal devices in the system. Each terminal device detects the moment at which the swept reference frequency passes through one of the resonant modes of its bus tap resonator and determines the elapsed time thereof from the system synchronization signal.