Abstract: In an infrared spatial communication system which comprises first and second data communication devices (1 and 2) and which carries out spatial communication from the first data communication device to the second data communication device by the use of an infrared ray, the second data communication device has a reflector (28) for reflecting, as a reflected infrared ray, the infrared ray which is transmitted from the first data communication device and which carries transmission data. The first data communication device has a transmitter (13, 14) for transmitting, in response to original communication data, the infrared ray which carries the original communication data as the transmission data. The second data communication device further has a receiver (25, 26) for receiving the infrared ray carrying the transmission data to produce the transmission data as primary reception data.

Abstract: An optical distribution network using optical fibers connects a central office terminal to a number of optical network units which service respective subscribers. In order to monitor the onset and pace of signal degradation in the individual fibers of the network, an optical carrier signal is modulated with an amplitude-varied signal including at least two different amplitude levels that are above a selected amplitude threshold. At least one of the amplitude levels is chosen so that a portion of the signal having the chosen amplitude will not be reliably detected when a fiber in the path between the central office terminal and a destination optical network unit fails to meet a specified threshold power margin.

Abstract: An optical transmission link has both a transmitter module and a receiver module operable under uncooled conditions, i.e., without the need of costly cooling equipment, such as thermoelectric coolers. The optical transmission system includes both a semiconductor laser diode source and an optical receiver module that are both designed to operate uncooled under high frequencies (e.g., GHz range) over a wide temperature range without significant changes in signal bandwidth and at temperatures in excess of 125.degree. C. Compensation is provided to reduce the effect of photodiode noise and amplifier noise. In addition, temperature compensation can be provided that provides for overall reduction in receiver noise across the bandwidth of the receiver module through maintenance of a temperature environment optimizing receiver performance.

Abstract: An optical communication network for quickly detecting faults and rerouting data using the optical signals in their light form, superimposes a monitoring signal on an optical data signal. The optical data signal and the monitoring signal are superimposed by, for example, wavelength-multiplexing or polarization-multiplexing. A receiving node receives the superimposed signal and splits it back into the optical data signal and the monitoring signal. A processor in the receiving node analyzes the monitoring signal to determine whether a fault exists in the transmission path. Similarly, the processor can analyze the data signal to determine whether a fault exists in a previous node or repeater. Once a fault is detected, the signal can be quickly rerouted (detoured) around the faulty section (node).

Abstract: For transmitting information via laser beams to and from other similar laser communication transceivers. Each transceiver comprises a wavelength locked beacon laser providing a beacon beam. The transceivers determine the precise location of other transceivers by detecting these beacon beams with beacon receive units comprising atomic line filters matched to the beacon wavelength. Signals are transmitted by imposing an electronic signal on laser beams produced by one or more signal laser devices. These signals are directed with precision at other transceivers, and the signal beams are detected with very narrow field of view signal receive units. In a preferred embodiment, these transceivers are installed on 66 satellites in low earth orbit and on selected mountain tops on earth to provide a global communication system.

Abstract: The optical amplifier combiner arrangement is used in a tree-like optical network (APON) comprising a cascade connection of dedicated branches, of the arrangement and of a common branch. The arrangement is coupled between a plurality of optical network users and an optical line terminator, via the dedicated branches and the common branch respectively. The network enables upstream transmission of information signals from the optical network users to the optical line terminator. The optical amplifier combiner arrangement includes for each branch of the dedicated branches (1) an optical amplifier to amplify an information signal with a gain value and to thereby generate an amplified information signal with a predetermined power level, (2) an optical on/off switch coupled between the optical amplifier and an optical combiner to pass the amplified information signal when the information signal is present and to interrupt the branch when the information signal is not present.

Abstract: An Add/Drop circuit for use in optical wavelength-division multiplexed systems includes fiber coupled four-port polarized beamsplitters and fiber Bragg grating filters.

Abstract: The present invention comprises an apparatus for communicating, monitoring, and gathering data from and with a plurality of electrical devices connected to predetermined points on a network of equipment. The present invention is particularly suitable for x-ray and vascular systems which have multiple pieces of equipment which require maintenance, repair, and adjustment. The apparatus of the present invention provides for faster repair and maintenance of vascular or x-ray systems through the use of an expert system which provides diagnostic and troubleshooting assistance to the field service engineer.

Abstract: A data access arrangement (DAA) having a transhybrid circuit for separating a transmit signal from a received signal by providing a transmit cancellation signal to the inverting input of a servo-feedback differential amplifier on the receive channel of the DAA. The cancellation signal is provided by a photodiode optically coupleable with a light emitting diode within a optical isolator on the transmission channel of the DAA. The gain of the cancellation signal can be independently controlled.

Abstract: In an optical communication system or method, two light signals having different wavelengths and different polarization directions are generated using a common modulation signal on a transmitter side, and the light signals transmitted over a light transmission line are wavelength-discriminated by a wavelength filtering unit disposed on a receiver side to demodulate a signal. The filtering unit may include a plurality of filters which are arranged so that the transmitted light signals of different wavelengths are respectively selected out thereby and a difference signal between outputs of the filters is produced to demodulate the signal.

Abstract: An electro optical circuit for transmitting an information bearing signal, such as a signal in the RF, AF or microwave frequency domains, to a predetermined location includes a laser for generating coherent light to be used as a carrier, and an electro optical modulator for receiving the information signal and the coherent light and generating first and second modulated light signals which respectively comprise the coherent light modulated by the information signal and the coherent light modulated by the inversion of the information signal. The first and second modulated light signals are supplied to a detector at the predetermined location through separate optical paths.

Abstract: An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.

Abstract: An all-optical time slot interchange device comprises at least two wavelength selective delay lines disposed in series and each comprising a delay line for delaying the propagation of an optical signal by increasing the length of the optical path it travels. An optical signal at a given wavelength is extracted from a guide structure and re-injected into the guide structure via the delay line so as to apply a time-delay to the optical signal at a given wavelength. Applications include wavelength-division multiplexing optical telecommunication systems.

Abstract: An information transmitting apparatus for efficiently transmitting input information coming from a plurality of transmitters wherein a receiver can determine the type of the transmitter from which the information was sent, the apparatus being produced at low cost and matching the conventional counterpart in signal reach distance.

Abstract: An optical communications device is disclosed which is equipped with a transmission unit adapted to send binary-coded electrical pulse signals to another optical communications device in the form of optical pulse signals. The transmission unit includes a modulator for producing an electrical pulse signal of a narrow pulse width only at each of rising and falling edges in the binary-coded electrical pulse signals and an electro-optic converter for converting the electrical pulse signal of a narrow pulse width into an optical pulse signal of a narrow pulse signal. As an alternative, the transmission unit includes a modulator which produces an electrical pulse signal of a narrow pulse width for each bit in the binary-coded electrical pulse signals only when it is at a high level and an electro-optic converter which converts the electrical pulse signal of a narrow pulse width into an optical pulse signal of a narrow pulse width.

Abstract: A fault signalling system for an optical fiber-based communications link having erbium doped fiber amplifier repeaters comprises a broadband optical source for generating a fault signal in the event of a fault occurring. Each repeater includes such a broadband source, which will output a characteristic fault signal onto the link for transmission to a receiving station, in the event of a fault being detected at that repeater. Advantageously, a control circuit which enables the source to emit its fault signal when appropriate is also used as part of an automatic gain control for the output of the amplifier repeater in normal operation.

Abstract: An electromagnetically controlled optical switch having a plurality of optical inputs. An optical signal at each input is spatially decomposed into two coparallel, orthogonally polarized beams by a birefringent element. An array of field-controlled polarization rotators are positioned in the paths of the decomposed light beams so that the polarization of the emergent beam pairs are set to be at one of the orthogonal states (i.e., both beams are either vertical or horizontally polarized). A following birefringent element spatially routes the light beam pairs based upon their polarization. A second array of polarization rotators follows the second birefringent element and is set to be in the opposite state from the first array, such that the emergent beams are orthogonal to their input states before they entered the first polarization rotator. The beams are combined by a birefringent element to form a plurality of combined beams that are coupled to output ports.

Abstract: In a power feeding system for an optical transmission system used as an optical submarine cable system formed by at least two cable landing stations, a power feeding cable is provided between the cable landing stations, and a plurality of optical repeaters are provided at predetermined intervals on the optical submarine cable. The power feeding system includes at least one constant voltage source provided for one end or both ends of the power feeding cable to apply an electric potential between the power feeding cable and the ground, and another constant voltage source provided in the cable landing station. In addition, the power feeding system includes an optical repeater connected between the power feeding cable and the ground to utilize the electric potential as a supply voltage for the optical repeater itself.

Abstract: An optical pulse propogating in an optical guide of an electro-optic medium interacts with a coplanar RF traveling wave to shift the optical wavelength. The RF phase is resynchronized to the optical pulse phase with spatial periodicity to provide a desired phase relationship between RF and optical radiation. A unidirectional incremental wavelength shifter comprises a frequency multiplexer for soliton communication and a symmetrical sideband modulator of this type varies the spectral width of probe illumination in an atomic absorption spectrometer probe beam.

Abstract: A chromatic dispersion compensator includes an optical circulator or a directional coupler having a first, second and third ports; an input transmission path connected to the first port; an output transmission path connected to the third port; a chirped grating connected to the second port; and a dispersion compensating fiber connected to at least one of the first, second and third ports. The dispersion compensating fiber and the chirped grating have chromatic dispersion characteristics which are opposite to the chromatic dispersion characteristics of the input and output transmission paths. In the wavelength compensator, the optical signal is incident into the first port from the input transmission path, and is made to go out to the chirped grating from the second port. Further, the optical signal is incident from the chirped grating to return to the second port, and is made to go to the output transmission path from the third port.