Abstract: Optical communications apparatus for sending and receiving optical transmissions to and from a plurality of remote stations by a plurality of independent terminals which are multiplexed so that all operate through a single optical system for both transmission and reception of modulated beams containing encoded data.

Abstract: In a wavelength multiplexed optical transmission system, digital signals of separate channels are respectively converted into optical signals of different wavelengths which are assigned to plural optical channels and multiplexed into a beam optical signal for coupling to an optical transmitted medium. Each of the optical channels includes a semiconductor laser for emitting a laser beam and an optical phase or frequency modulator for modulating the laser beam with one of the digital input signals. A light intensity limiter, or a laser diode saturable light amplifier is located in the path of the light from the modulator to maintain the modulated laser beam at a constant amplitude to prevent interchannel crosstalk which would otherwise occur in the transmission medium as a result of variations in the output of the laser and/or modulator.

Abstract: A communications systems is characterized by a pulse-shaping technique for producing shaped, stabilized, ultra-short (picosecond to femtosecond) pulses containing encoded information. Pulse shaping is accomplished by temporally stretching and chirping an ultra-short pulse from a pulse generator, modulating the pulse in real time and temporally compressing the pulse in a manner so as to cancel the original chirp.

Abstract: A radio-optical transmission system in particular for space telecommunications, comprising a radio-optical interface between a first modulated radio wave (15) and a light wave (18), wherein the transmitted light wave (18) is subjected to wavelength modulation.

Abstract: In the pulsed FM system, the input signal is first modulated into the pulse FM signal. Thereafter, this pulse FM signal is modulated into the pulsed FM signal by the frequency divider. This pulsed FM system is suitable to CATV.

Abstract: A wavelength division multiplexer/demultiplexer having optical path lengths between a fiber array and a Fourier transform lens, and between a dispersion grating and the lens equal to the focal length of the lens. The optical path lengths reduce losses due to angular acceptance mismatch in the multiplexer. Close orientation of the fiber array about the optical axis and the use of a holographic dispersion grating reduces other losses in the system. Multi-exposure holographic dispersion gratings enable the multiplexer/demultiplexer for extremely broad-band simultaneous transmission and reflection operation. Individual Bragg plane sets recorded in the grating are dedicated to and operate efficiently on discrete wavelength ranges.

Abstract: A fiber optics communications network system that is adapted for operation with either electrical or optical central office functions, i.e. switching and routing functions, is adapted for connection to electrical or fiber optic conduits for subscriber entrance sites, and which is composed of passive and inert components except for optical modulating devices at communications-transmission stations. The system is characterized by use of a train of pulses supplied to receiver lines and, most advantageously, use of an ancillary pulse in selection and amplification of individual signals for reception by receiver stations and time-division-demultiplexing. In preferred embodiments, the transmission side of the system is assigned a fixed optical frequency address and a fixed time slot is assigned to each transmission station.

Abstract: An optical time slot interchanger which interchanges one optical pulse at a time in a bit interleaved format. The optical time slot interchanger is constructed from an N-bit serial-to-parallel converter and N optical memory cells, each of said optical memory cells being optically coupled to a parallel output port of said optical-to-serial converter. The ouputs of all N optical memory cells are optically coupled to form a single output port for the time slot interchanger. The optical time slot interchanger has a single input port to receive serially a frame of N optical pulses and a single output to present serially said frame of pulses with interchanged time slots. As a frame of N optical pulses enters the optical time slot interchanger, they are shifted and stored in said optical serial-to-parallel converter under the control of clock means. The optical pulses are then shifted to optical memory cells to await serial output in a time slot interchange under control of other clock signals.

Abstract: A technique for increasing the number of manufactured laser transmitters which meet a predetermined wavelength specification is disclosed. Semiconductor lasers which exhibit a relationship between operating temperature and wavelength can be tuned by adjusting the operating temperature to ensure that the transmitter's operating wavelength will fall within the system-specified limits.

Abstract: An optical communication system suited for transmitting optical signals to a moving station located on a vehicle comprises a transmitting station to send out coded optical pulse signals through space and a receiving station to receive the pulse signals. The transmitting station comprises a data input device, a signal encoder to convert the data into coded signals, an optical pulse signal generator to deliver the coded optical pulse signals, and a transmitting path setter to set a space path for transmitting the optical pulse signals. The receiving station comprises a receiving device for receiving the optical pulse signals transmitted from the transmitting station, a signal decoder to decode the optical pulse signals into coded signals, and a data display to represent the data in visible form based on the coded signals. The transmitting device may provided with an external light shade for preventing the receiving surface of the receiving device from external lights.

Abstract: The invention relates to a method for compensating, in a coherent optical communication system with heterodyne detection, at the receiving side phase noise of the transmitting and of the local laser. Characteristic of the present method is that the phase-noise compensation takes place in the LF domain. The two MF heterodyne signals (Imf and Pmf) are first demodulated into LF signals (in which there is still noise), which are subsequently subtracted from one another, due to which the respective noise components cancel out each other. Preferably a local laser signal which is, qua frequency, between the two other HF signals is chosen. This offers the advantage that the two MF heterodyne signals can be modulated by one and the same demodulator; because for the compensation of phase noise the demodulated MF signals (Iif respectively Pif) which are, qua phase noise, in opposite phase with regard to each other are then added to one another.

Abstract: The present invention relates to a multichannel multihop lightwave communication network which allows packet concurrency in the network while avoiding the need for agile optical devices. The network comprises a lightwave communication medium (10) for supporting a plurality of independent user nodes; and a plurality of N network interface units (NIUs) (11). Each NIU is connected to the lightwave medium and one or more separate user nodes and comprises a trnasmitter section (28-35) and a receiver section (20-27) which are each fixedly assigned to transmit and receive, respectively, over a single channel or a plurality of separate channels to or from other NIUs of the network. In a connectivity pattern for one embodiment of the network, the NIUs are divided into k groups of p.sup.k NIUs such that each NIU of a first group of p.sup.

Abstract: In an optical apparatus for pulling an intermediate frequency in a predetermined frequency range, a local oscillation light source is swept in an oscillation frequency thereof in accordance with a signal applied to a frequency adjusting terminal thereof. The signal is of a counted value of a counter which counts pulse signals of an oscillator. When an intermediate frequency is pulled in a predetermined frequency range including a predetermined intermediate frequency, the counter is stopped to count the pulse signals, and is controlled to hold a then counted value which will be a fixed driving signal for the local oscillation light source.

Abstract: The invention relates to a system to transmit digital signals reproduced from a compact disk player, a digital audio tape recorder or the like. In order to increase the S/N ratio of transmission of the digital signals, the occurrence probability of data to be transmitted is made low and light emission time of a light emission element is made small, and the peak value of emission is increased corresponding to the above reduction. As a result, the S/N ratio can be increased in the same transmission band as that in the prior art. In order to reduce the occurrence probability of data, a method of generating pulses at the leading edge and the trailing edge of a pulse signal or a method of compressing data is provided.

Abstract: An electro-optical transducer assembly for translating between an optical high speed serial data transmission path and parallel electrical data transmission paths is provided by a light emitting or light detecting device with serial terminals, a logic chip with timing, amplifying, serializing or de-serializing circuitry, and a multi-layer coupling chip with parallel input or output contacts mounted between the device and the logic chip for coupling the serial terminals of the device to the serial terminals on the logic chip and coupling the logic chip parallel terminals to the parallel input or output contacts.

Abstract: In an optical fiber communication system that operates at a wavelength .lambda..sub.o and comprises optical fiber having a cut-off wavelength .lambda..sub.c >.lambda..sub.o, a "grating", with parameters chosen such that the grating causes resonant coupling between a predetermined guided mode (e.g., LP.sub.11) and a tunneling-leaky mode, can be advantageously used to remove unwanted guided modes. Such removal can substantially improve the bandwidth of such a system.

Abstract: A multi-channel wideband monomode optical fibre network having at least one transmitting station and a plurality of receiving terminals connected to the transmitting station by monomode optical fibres. One or more sources of temporally coherent optical power, for example laser transmitters are connected to the network to feed optical power locally to the receiving terminals. The number of sources is less than the number of terminals.

Abstract: An emission device includes a first electro optical converter for converting electrical energy from a supply source into optical energy. A second electrical converter is provided to convert the electrical energy into digital information which is converted into digital optical information by a second electro optical converter. A reception device includes two optoelectrical converters connected to the electro optical converters by an optical path, and an electrical power accumulator capable of storing said electric power delivered by said optoelectric converter. The power accumulator is capable of supplying the reception device with electric power.

Abstract: A three level network microprocessor based nodal architecture for a fiber optic local area network communication system is disclosed in which the processing responsibility for establishing a voice, video or data communication link between an initiating I/O device and a recipient I/O device and for subsequent two way data exchange between the initiating and recipient devices are shared between three levels of digital processing capability in such manner as to demand the least amount of time from the highest, most intelligent processing level common to all devices thereby making more efficient use of its processing capability as an overall supervisory processor. Each I/O device whether it be a digital terminal, computer or telephone set interfaces with a nodal system through a middle level of processor.

Abstract: A fiber-optic switch uses a single optical fiber for two-way communication with light. A switching mechanism has no electrical part and is thus appropriate for placement in an area having explosive or combustible material. The optical fiber can be cut to length in the field and can be installed without special tools or training. The fiber is held in place by a clip that is constrained to compress the fiber and grip it securely. A snap-action mirror reflects light back into the fiber in one position and does not reflect it in another position. An electronic circuit provides pulsed light and determines coincidence of sent and received pulses to discriminate against operation of the switch by ambient light or other spurious signals.