Abstract: A two way transmission system has a source at one terminal and a fibre loop at the other terminal. Conventional modulation techniques are used at the terminal with the source, whereas at the other terminal modulation is achieved by modulation of the birefringence of the loop.

Abstract: A first (1) and a second (6) narrowband laser device (1, 6) are each connected to an optical coupler means (3, 8) and also to each an input (13, 14) of a directional coupler (15). The coupler means (3, 8) have their respective outputs (5, 10) connected to a photo detector (18). The laser devices (1, 6) are each connected to their respective control circuit (17, 20). The control circuit (20) of the second laser device (6) is in turn connected to the output (19) of the photo diode (18) and to an exterior control signal (V2) with a frequency f.sub.0. Controlled by its control circuit (17) the first laser device (1) transmits a light signal (S1) with a fixed frequency f.sub.1, and the second laser device (6) transmits a light signal (S3) with a frequency f.sub.2. The photo detector (18) transmits a signal (V1) with a frequency f.sub.2 -f.sub.1 and the second control circuit (20) controls the second laser device (6) so that f.sub.2 -f.sub.1 =f.sub.0. An information carrying signal (V.sub.

Abstract: An image processing system of the invention has a reader which reads out an image of an original, a page memory which stores image information of the original in the form of electric signals, a disk memory which stores part or all of the image information in the disk memory and also stores image processing information, an image processing section, a digitizer for the operator to input the image processing information, a CRT which displays input information or corrections in conversation language, a DMA controller, and a printer. The image processing system of the invention is capable of DMA transfer without the intermediacy of a CPU. Fewer addresses are required for readout of the image information from the memory, and high speed image processing is achieved.

Abstract: An optical homodyne receiver is realized by employing two separate signal amplification paths in a balanced receiver configuration. Specifically, the relative phase difference between a received optical signal and a local oscillator signal is extracted from nodes which, from the point of view of an amplifier extracting a data component signal, are at ac ground. This approach permits a phase detector amplifier, which extracts the relative phase component, to be dc coupled in addition to having a higher transimpedance for lower thermal noise, and thus higher sensitivity. Additionally, by extracting the data and phase component signals at different points in a balanced receiver configuration, the data and phase amplifiers can be separately engineered for optimum performance.

Abstract: A multiple-input power control system accepts control signals from a radiant signal transmitter and from a local control, selects one of the signals, and provides the selected signal to a power controller to control the power to a load. At least one of the control signal sources has an actuator which is movable through a range of positions, to determine the control signal provided by that source. The system finds particular utility in controlling lighting loads.

Abstract: A time and wavelength (T.times.W) switch comprises a plurality of wavelength selectors for selecting a time division multiplexed (TDM) channel of a first wavelength from a plurality of incoming TDM channels of different wavelengths. A plurality of time-slot switches are connected respectively to the outputs of the wavelength selectors for switching a first time slot of the selected TDM channel to a second time slot. To the outputs of the time-slot switches a plurality of wavelength converters are respectively connected for converting the wavelength of the second time slot to a second wavelength. The T.times.W switches can be arranged as an incoming time and wavelength switching stage and an outgoing time and wavelength switching stage. An array of optical devices interconnecting the outputs of the incoming and outgoing stages constitutes an intermediate stage.

Abstract: An optical switch for use in a fiber optic telecommunications network is disclosed. An important feature of the inventive switch is its multicast capability. The inventive switch utilizes two internal networks, an optical network for transmission and an electronic network for control. Illustratively, the transmission network is an optical star network which links the input ports and output ports of the invention switch. The electronic control network is in the form of a track of ring which surrounds the optical star and sequentially connects the input and output ports.

Abstract: An optical signal receiver comprising an optical mixing/polarization splitting unit for producing IF optical signals having two orthogonally polarized components, an optical signal receiving unit for producing four corresponding IF electric signals, and a combining circuit for combining two IF electric signals having one polarization with the other two IF electric signals having the other polarization, suppressing fluctuation of the polarization and the intensity noise of the related local optical signal. The intensity noise suppression is also effective for IF electric signals having a higher frequency range.

Abstract: An optical heterodyne or homodyne receiver includes a single constructively integrated optical component which combines a local oscillator beam with a signal beam to derive oppositely phased combined beams and further splits each of the combined beams into orthogonally polarized sub-beams. The integrated optical component has a polarization-sensitive beam-splitting layer in a first plane and a polarization-insensitive beam-splitting layer in a second plane, the two planes being perpendicular or parallel to each other.

Abstract: Disclosed is a time division multiplexed optical communication system that is capable of operation at relatively high bit rates and that is relatively stable and immune to crosstalk and noise. The system comprises receiver means wherein the timing signal for demultiplexing is derived from the fully multiplexed optical pulse stream by means that comprise a narrow band receiver and timing means that produce a lower-frequency timing signal from the output of the narrow band receiver. The timing signal is used to drive one or more optical switches. In one embodiment of the invention the receiver means have a binary-tree architecture and the timing signals are substantially sinusoidal. In another embodiment the receiver means have a linear-bus architecture and the timing signals are pulse-like.

Abstract: An optical multiplexer and demultiplexer using combined code division and wavelength division multiplexing. The multiplexer comprises a plurality of code division multiplexers, each responsive to a plurality of input signals and a plurality of orthogonal code sequences, and a wave division multiplexer for generating an output signal representing the signals of each code division multiplexer carried on a different wavelength. Each code division multiplexer comprises a plurality of lithium niobate phase shifters, each comprising an indiffused titanium wave guide and a pair of electrodes for the accepting one of the orthogonal code sequences, to modulate the light wave being passed thrugh the wave guide.

Abstract: An optical communication system in which a group, or "comb", of intelligence-bearing signals are frequency-division-multiplexed and stabilized using a corresponding "comb" of resonances associated with a Fabry-Perot cavity.

Abstract: An optical communication system includes a transmitter for a generating a subcarrier multiplexed optical signal, a receiver and an optical fiber for coupling the optical signal from the transmitter to the receiver. At the transmitter, an optical carrier is modulated with a composite modulation signal including a plurality of modulated microwave subcarriers to provide the optical signal. The receiver includes a local oscillator for generating a local light beam, a detector responsive to the received optical signal and the local light beam for providing a detected signal at an intermediate frequency, and a microwave receiver for demodulating the microwave subcarriers from the detected signal. The modulation index of the optical signal produced by each of the modulated microwave subcarriers is selected to permit transmission of a large number of high quality video channels. A quadrature detector can be used to eliminate second-order intermodulation products.

Abstract: In a four level FSK optical communication apparatus, signal light which is modulated in FSK with information is transmitted through an optical transmission line. The signal light is detected in an optical heteroclyne system by using local oscillation light, thereby producing intermediate frequency band signal which is then demodulated. A detection system comprises first and second delay detection circuits. In the first detection circuit, the intermediate frequency band signal is divided into first and second signals. The first signal is delayed by a delay time, and then mixed with a second signal which is not delayed to produce first delay detection signal. In the second delay detection circuit, one of the first signal delayed and the second signal not delayed is shifted in its phase by .pi./2. Then, signal having the phase shift of .pi./2 and signal having no phase shift are mixed to produce second delay detection signal. Thus, the demodulation of four level FSK modulation signal is performed.

Abstract: A laser beam communication system for spacecraft in which each communication terminal comprises, for steering the beam projected from that terminal, four mirrors, each mounted on a mechanism capable of rotating the mirror about a constant defined axis. The mirrors and their attached mechanisms are arranged in pairs with one pair on either side of a magnifying telescope. All rotating joints in each mechanism are constructed using flexure pivots. Such a pointing element can provide both the range and accuracy required for an important class of free space laser links without introducing any extra friction into the pointing system.

Abstract: A two way communication system is described wherein a base unit can transfer information with remotely-located unit such as a portable infrared commuicator. The base unit produces carrier frequency signals to a plurality of distributed transmitter modules which expose different areas to infrared transmissions. A plurality of down-link or base unit associated infrared detection modules are distributed to receive infrared carrier frequency communications from one or more remote or portable units and convert these to electrical signals at the same carrier frequencies. The latter electrical signals are delivered to the base unit through a common cable. This cable also serves to deliver electrical power to the base unit to the latter modules. The electrical carrier frequency signals are combined at the base unit which uses this to provide the base unit with the information detected from the remote unit and produce a signal representative of the detected infrared energy.

Abstract: The present invention is an apparatus for wireless communications of information between two locations. A transmitter means modulates the information into infrared radiation at a first location. The infrared radiation is transmitted by the transmitter to a reflecting surface along a straight line path which is transparent to the infrared radiation. The infrared radiation is reflected at the reflecting surface forming reflected infrared radiation. A receiver means for receiving the reflected infrared radiation from the reflecting surface is positioned at a second location. The second location and the reflecting surface have a straight line path therebetween which is transparent to the infrared radiation.

Abstract: An optical communications network comprises a number of remote stations connected to a node by optical fiber transmission paths interconnected by power dividers, each remote station including an optical transmitter operating at a peak power and a low duty cycle for a short period. Typically the optical transmitter is enabled to transmit information for only 10% or less of the total time and for a maximum of 500 ns.

Abstract: A fiber optic telephone system is described in which a plurality of subscribers with different bandwidth subscriptions are each connected to the system by an optical fiber subscriber connection. Use of the subscriber connection beyond the subscription bandwidth is prevented by the installation of a bandwidth limiting device having a maximum transmitted bandwidth capacity above that of the subscription bandwidth but below that of the total bandwidth capacity of the subscriber connection.

Abstract: The object of the disclosure is to construct an insert which, given the simplest structure, is optimally insulated and and voltage-stable. This goal is achieved in that the insert is composed of a jacket housing of highly insulating synthetic, for example, amino-butadienestyrol (ABS) or the like, and of a layer packet comprised of at least two shielding plates of, for example, aluminum or sheet steel, with a printed circuit board structure seated between them as a carrier for those components which are required for the energy and/or signal transmission, said layer packet being designed so as to be insertable into the highly insulating jacket housing.