Abstract: A multi-stage network which achieves the same overall connectivity as known networks but where individual switching nodes have no input selectivity and no output selectivity. Each node is enabled or disabled to control communication therethrough in response to a single control signal. The functionality of a switching network is achieved by controlling which nodes are enabled rather than specifying connections of particular node inputs and outputs to be effected by the nodes. In a photonic network embodiment, each network node is implemented using a single symmetric self electro-optic effect device (S-SEED).

Abstract: A wireless optical short-range communication system adapted for use as an intercom system. The system can be used in fast food restaurants and similar commercial institutions. The communication system includes a base station to interconnect via optical communication a group of substantially similar physically spaced-apart, remote units. Each one of the remote units and the base units includes an optical emitter to transmit an optical message-carrying beam to the base station, and an optical receptor to receive an optical message-carrying beam from the base station. The base station includes a receptor for receiving the optical beam transmitted by the optical emitters of all of the remote units, and an optical emitter to relay the received optical beam to the optical receptors of all the remote units.

Abstract: An optical pulse packet at electronic data rates is time-compressed in a recirculating optical delay line to produce a compressed optical packet which, after transmission over a high speed optical network, is expanded at optical data rates by use of the inverse of the compression process. The system employs two recirculating optical loops per network node, one for optically compressing a fully formatted electronic packet for transmission onto the network and one for electronically expanding such a packet upon reception.

Abstract: An optical subscriber network transmission system comprises a first optical transmission line transmitting information from center to a subscriber and a second optical transmission line transmitting information from to the subscriber to the center. A plurality of auxiliary optical transmission lines are disposed between the center and the subscriber.

Abstract: The present invention is for a radiation transmitter which transmits radiation to an illumination spot for forming reflected radiation. The transmitter includes a plurality of radiation transmission sources. Each of the sources transmits to a portion of the illumination spot. The transmitter includes means for alternately activating a portion of the transmission sources to illuminate a portion of the illumination spot for aligning a radiation receiver to receive the reflected radiation.Each resident of network transmits in turn its address and the address of each resident that it recognizes. Once a prospective resident can recognize each resident of the network it announces that it is joining the network and states its new address and the address of each resident it can see. Every resident then amends its list of recognized residents to include the new member.

Abstract: A fault examining apparatus is provided in a loop network system, in which a master station is connected sequentially with a plurality of follower stations in a loop transmission path to transfer digital optical signals denoting serial data information from the master station to the follower stations, from the follower stations to the follower stations or from the follower stations to the master station. The apparatus includes a device for detecting and storing a present value, a maximum value and a minimum value of a peak level value of received optical signals, and a display device for displaying the values.

Abstract: The disclosure is directed to an apparatus and method for receiving and processing an optical signal representative of electronic information. In an embodiment of the invention there is provided a light-emitting diode which is reverse biased to receive the optical signal and convert the optical signal to an electronic signal. Means are provided for determining time periods during which the electronic signal produced by the light-emitting diode is below a predetermined threshold. Means are provided for generating a dark current error signal indicative of a sampled output of the light-emitting diode during said time periods. Means are also provided for holding the error signal during other time periods when the electronic signal produced by the light-emitting diode is not below the predetermined threshold. Finally, means are provided for modifying the electronic signal produced by the light-emitting diode as a function of the held error signal to obtain an output electronic signal.

Abstract: An optical crossbar switch includes a plurality of input integrated optical couplers connected to a star coupler at one end of an optical cable and a star coupler coupled to the other end of the optical cable connected to plurality of output integrated optical couplers. Discrete parallel optical input signals are fed to each of the input integrated optical switches and clock signals in a time division multiplexed switching sequence switch the parallel optical signals to serial form for transmission over the cable. Clock signals are connected to actuate the output integrated optical couplers in a synchronized, time division multiplexed switching sequence at GHz rates to assure the responsive transfer of a number of signals without the consequences associated with the excessive losses attendant conventional spatial light modulator interconnections.

Abstract: A fiber optic distributed temperature sensor system outputs a temperature distribution along the longitudinal direction of a sensor optical fiber by measuring the temperature dependency of Raman scattered light intensity produced in an optical fiber by use of the OTDR technique. The system is characterized in that a light output from a light source is input to the sensor (optical fiber) via an optical wavelength division demultiplexer, that among the reflected light of back scattered light returning from the sensor optical fiber, light of a particular wavelength range is reflected or transmitted by at least one optical filter of the optical wavelength division demultiplexer to separate the light of the particular wavelength range and that signal of the light of the particular wavelength range is guided to a detector of an optical measuring system.

Abstract: In an optical communication network for multiplex operation, a light waveguide is conducted up to a branching point proceeding from a respective distributing location. A division of the signals into two sub-signals with a directional coupler occurs at this branching point. A second light waveguide that is connected to the second input of the directional coupler is additionally laid between the distributing and the branching point. A switching onto the second light waveguide is provided. A system is described for two-way management using a pair of direction couplers connected crossed to a plurality of direction couplers on the subscriber side.

Abstract: When the subscribers are connected with the switching system by the optical fibers, in order to realize the signal exchange without converting the optical signals sent by the optical fibers into the electric signal, the optical switching system is constituted by: an optical time division multiplexer for time division multiplexing the optical signals which were sent by a plurality of fiber optic cables corresponding to a plurality of subscribers; an optical time switch for changing the time arrangement of the output signals of the optical time division multiplexer; and an optical time division demultiplexer for distributing the time sequential signal of the output signals of the optical time switch to the optical fibers of a plurality of subscriber lines.

Abstract: An optical transmission apparatus is disclosed which comprises a light emitting element for outputting an optical output in order to transmit data, a current modulation circuit, a bias current generating circuit and a resistor circuit connected in parallel with the emitting element. The current modulation circuit supplies a binary modulated current to the emitting element in response to an input binary data to the transmitted, the bias current generating circuit provides a bias current to the emitting element and the resisor circuit, whereby said bias current is kept higher than a specified level.

Abstract: An image transmission system includes an image transmitting unit having a display to display a status of a receiving unit and a detector for detecting a size of an original and a record mode permitted for transmission.

Abstract: An asynchronous time-division multiplex optical communication system comprises: a switching network, user transmitter circuits, user receiver circuits and broadcast servers connected by optical lines to the switching network. The switching network comprises an optical spectro-time-division switching network, a control processor unit and a clock unit. The spectro-time-division switching network is connected optically to the user transmitter circuits, to the user receiver circuits, to the broadcast servers and to control transmitter, signalling transmitter, control receiver and signalling receiver circuits of the control processor unit. The clock unit is connected by a first line to the switching network and by a second line to the control processor unit which is connected by a control bus to the spectro-time-division switching network. The system uses conjointly a first set of optical frequencies for transmission and a second set optical frequencies for switching.

Abstract: Apparatus for optical transmission of first and second digital channels. Each digital channel has first and second signal levels. The appparatus has a tunable laser for emitting an optical output at optical frequencies corresponding to current levels. Current responsive to the signal levels of the two channels provides current levels to cause the laser to emit a first optical frequency when the first channel has a second signal level and the second channel has a second signal level, a second optical frequency when the first channel has a first signal level and the second channel has a second signal level, a third optical frequency when the first channel has a first signal level and the second channel has a first signal level, and a fourth optical frequency when the first channel has a second signal level and the second channel has a first signal level. An optical transmission medium is coupled to the output of the laser. A tunable optical filter is coupled to the optical transmission medium.

Abstract: A photonic time-slot interchanger with fiber-loop delay-line memories is provided with multistage, cascade-structured integrated optical switches in the write-in, store and circulate and read-out functions to provide improved signal-to-crosstalk ratios and control tolerances, and to increase significantly the number of time slots supported by the improved interchanger.

Abstract: A communications network comprising a plurality of "subnetworks" multiplexed onto a single communications medium. A separate group of NIU's communicate on each predetermined "subnetwork", and each NIU also includes a tunable transmitter for transmitting data to NIU's of other subnetworks. Data from a user equipment is transmitted via the tunable transmitter if it is destined for an NIU from another subnetwork, and via a fixed transmitter if it is destined for an NIU on the same subnetwork. In one embodiment, fiber optics is utilized in order to provide a high speed network with tunable lasers.

Abstract: A fast packet and frequency switch, with inputs and outputs connected to optical fibers, each allowing the transit of a certain number of different-wavelength optical carriers, modulated by serial information flows organized into packets. The packets are phase-realigned and their labels are converted under the control of external processors designed to set-up and break connections. Then a frequency conversion of the optical carriers allotted to packets is carried out and the packets are recombined into a single fiber by a passive recombination network in order to be stored into an optical loop memory, which is an optical fiber delay line. Each optical packet flow is extracted at suitable times, is frequency-converted and, among the various frequencies obtained, there are selected only those to be sent to corresponding output fibers outgoing from the switch, after having been recombined with those of the other converted flows.

Abstract: Method and device for the optical filtering and photodetection of intensity-modulated optical signals.Signals are injected into at least one resonating type semiconductor laser amplifier (2) close to the active layer (14) of this amplifier, the latter being polarized below its threshold current and having at least one resonance wavelength adjusted so as to coincide with the wavelength of at least one of the optical signals in order for this optical signal to be amplified by the amplifier, and the voltage existing between the terminals of the amplifier is detected so as to obtain, in the form of an electric signal, the information carried by the amplified optical signal when the angle between the polarization direction of the latter and the direction of the active layer is small.Application for the embodiment of optical receivers.

Abstract: Apparatus for optical transmission of first and second digital channels. Each digital channel has first and second signal levels. The apparatus has a tunable laser for emitting an optical output at optical frequencies corresponding to current levels. An input which provides a current responsive to the signal levels of the two channels provides current levels to cause the laser to emit a first optical frequency when the first channel has a first signal level and the second channel has a second signal level, a second optical frequency when the first channel has a first signal level and the second channel has a first signal level, a third optical frequency when the first channel has a second signal level and the second channel has a first signal level, and a fourth optical frequency when the first channel has a second signal level and the second channel has a second signal level. An optical transmission medium is coupled to the output of the laser. A local oscillator provides a LO frequency.