Abstract: A growable packet switching arrangement where the number, S, of distribution network stages is reduced by bounding S according to log.sub.2 (max(L,N))<S+1<[log.sub.2 (max(L,N))].sup.2 /2. Since the distribution network is made up of stages of opto-electronic nodes and interconnecting free-space optical link stages, there is no need to transmit input signals using different frequencies. Input signals are instead distinguished based on their spatial location. Accordingly, there is no receiver tunability restriction on L, the number of inputs. Further, because signals are regenerated at each network stage and there is only a 3:1 power loss (approximate) at a given stage, high signal/noise ratios and corresponding low bit error rates are achieved.

Abstract: A light transmitter for preventing the degradation of the extinction ratio and the occurrence of pulse width distortion in the light output in spite of the variation of current to light conversion efficiency A of the laser diode. The transmitter uses the characteristics such that the light pulse width becomes narrower than the modulation current pulse width if the laser diode is modulated by a bias current smaller than the threshold level. The light transmitter includes mismatch detection circuit (14) which detects the decrease of the light pulse width. By the detected mismatch signal, the modulation current control circuit (15) limits to increase the modulation current. The modulation current control circuit (15) operates together with the control circuit which controls automatically the light output peak value to be constant.

Abstract: A covert communication system uses ultraviolet light rather than radio waves as a medium for communication. Suitable wavelengths are chosen by examining atmospheric penetration, attenuation by clouds, presence of interfering sources, and ease of generation and detection. The transmitted ultraviolet light may contain both voice information and other data, impressed upon the light by frequency or pulse modulation using a Pockels cell light modulator. A corresponding receiver can be arranged as a transponder to determine range by phase angle differences between transmitted and reflected waveforms. By using an appropriate lens, the receiver can also determine the angle of incidence of a detected ultraviolet signal, and therefore the bearing of the transmitter.

Abstract: A light frequency communications system and method of using the system is disclosed. The system includes a base station and a plurality of remote units wherein the base station and all the remote units communicate in a full duplex mode utilizing a single light wave carrier. Multiplexing between the units is accomplished by modulating an audio signal on at least one subcarrier frequency.

Abstract: A switching device for being connected to switch optical input signals received on a plurality of optical input signal lines into optical output signals on a plurality of optical output signal lines; each device has a time slot interchanger or a wavelength converter in combination with a space-division switching stage for freely exchanging signals on different lines, wherein, according to the invention, such a switching device has multiple stages, including both a time slot interchanger stage and a wavelength converter stage in combination with two space-division switching stages and wherein between every two of the space-division switching stages a time slot interchanging or wavelength converting stage is inserted; the time slot interchanger stages may alternate with wavelength converter stages with a space-division switching network stage in between.

Abstract: An optical transceiver is provided for transmitting a light pulse to a target and for receiving a reflected light pulse from the target. The transceiver includes a light source for transmitting a coherent light pulse which is reflected by the target along a first optical path as a reflected light pulse. The transceiver also includes a trigger signal generating circuit, coupled to the light source, for generating a trigger signal to indicate when the light pulse is transmitted. The transceiver further employs an attenuation device, responsive to the trigger signal and situated in the first optical path to intercept the reflected light pulse, for attenuating optical transmission through the first optical path inversely as a function of time from generation of the light pulse. In this manner, reflected light pulses reflected from targets close to the transceiver receive a greater amount of attenuation than reflected light pulses reflected from more distant targets.

Abstract: Apparatus and method for large scale asynchronous transfer mode (ATM) switching utilizing tunable lasers and fixed-tuned receivers are provided. The apparatus, an optical switch, includes a plurality of input modules for receiving ATM cells to be switched and a plurality of output modules for outputting the switched ATM cells. The optical switch also includes an optical transmission network for optically transmitting each ATM cell from an input module to a particular output module, and a contention resolution device in electrical communication with the plurality of input modules for selecting the ATM cells from the plurality of input modules to be switched. Preferably, each output module includes a plurality of fixed-tuned receivers and each input module includes a plurality of tunable lasers. The fixed-tuned receivers of each output module are tuned to a particular wavelength so as to pass only those ATM cells optically received from the optical transmission network at the particular wavelength.

Abstract: An optical communication system for obtaining transmission of information with a pumping light beam acting as carrier, in addition to transmission of information with a signal light beam. This optical communication system includes an optical fiber amplifier amplifying a signal light beam by having the signal light beam and a pumping light beam propagated through a rare-earth-doped fiber, and a modulating circuit for modulating the pumping light beam with a high-frequency modulating signal having a period shorter than the life span of fluorescence resulting from an excited state.

Abstract: A signal transmission protected against undesired quering is made possible with a photon-driven component and the energy supply is independent of external electrical connection. A photon-driven device has a light-receiving, monolithic semiconductor component for receiving optical energy and an optical signal for conversion into electrical energy and an electrical signal and has a light-transmitting semiconductor component for converting the electrical signal into an optical signal and for transmitting the optical signal. A radiation source for producing the optical energy and the optical signal and an optical receiver for the output optical signal from the photon-driven component are provided in a device for reading the information carried by the optical signal and produced in an electrical circuit connected to, powered by and operated by the photon-driven semiconductor component.

Abstract: A protection arrangement protects an optical transmitter device with n optical transmit circuits or an optical receiver device with n optical receive circuits. It includes fault evaluating circuitry to detect a defective transmit/receive circuit, a spare transmit/receive circuit, and switching circuitry. Upon detection of a defective transmit/receive circuit by the fault evaluating circuitry, the fault evaluation circuitry controls the spare transmit/receive circuit and the switching circuitry to bypass the defective transmit/receive circuit with the spare transmit/receive circuit.

Abstract: A system for optically transmitting a useful signal (S.sub.1) from a transmitter (1) over a transmission link which includes either an optical waveguide (3) or a fiber-optic network coupled to a receiver (2). The transmitter (1) transmits the useful signal (S.sub.1) and an auxiliary signal (S.sub.2) over the transmission link toward the receiver (2) at different wavelengths. Circuits (4a, 4b, 5, 6, 7) at a desired point in the transmission link and analyze the auxiliary signal (S.sub.2) and provide a response signal (S.sub.3) containing information for monitoring the useful signal. The transmitter (1) receives the response signal (S.sub.3) and controls the further transmission of the useful signal (S.sub.1) and the auxiliary signal (S.sub.2) in accordance with the information in the response signal (S.sub.3).

Abstract: An exemplary packet processing apparatus where a large number of comparisons can be made concurrently in bit-parallel fashion by partitioning the comparison functionality to two optoelectronic integrated circuits, and interconnecting the two circuits using free space optics. Illustratively, different embodiments are used to perform one-to-many or many-to-one comparisons by developing multiple copies of one value for concurrent comparison with many possible values. The invention is more generally applicable to other comparison applications where one-to-many or many-to-one comparisons are made.

Abstract: A low blocking packet distribution network which is implemented in optics. The network has both switch links and chute links, and the network nodes include both a switching devices interconnecting successive stage switch links and a plurality of non-switching, chute connections interconnecting successive stage chute links. A network node can transfer a packet, being received on a switch link, to any selected one of the chute connection means of that node for transmission on a chute links. The network nodes are relatively simple and inexpensive because they store only the first few bits needed to route an ATM cell. The blocking probability is further reduced when the number of chutes per node is increased. The number of chutes may be based, for example, on the number of switch link inputs per node.

Abstract: In a transmitter including a carrier source an input signal is present which contains the information to be transmitted and is composed of signal components having amplitudes less than a predetermined threshold value or equal to the threshold value and signal components whose amplitudes are less than the threshold value or equal to the threshold value. For the purpose of identification, the two signal components are sampled in different ways, for example at different frequencies and are combined into a modulation signal in such a manner that the two signal components have the same sign. In a receiver, a circuit arrangement is provided which identifies the sign of the partial signals on the basis of their different sampling frequencies, demodulates envelope curves and combines them into an output signal which corresponds to the signal.The transmitter and receiver are advantageously components of an analog optical transmission system.

Abstract: An optical line shelf formerly used exclusively for multiplexing broadband video with voice channels in a serial bus transport format is adapted for use with both optical line distribution units and a metallic distribution unit.

Abstract: In a system of optical communications that can be used by air or space vehicles, each station comprises at least one optical system covering a half space, this system comprising two twinned optical devices to respectively form two distinct reception channels: a first reception optical channel for the initialization, in space, of the direction of communication; a second optical channel for the reception of the contents of the communication. One of the two optical devices is also used to form a transmission channel for the initialization and then for the communication in the direction of communication. The setting up of communication is done in three steps, respectively target designation, iterative bilateral acquisition and interstation communication.

Abstract: An optical fiber telecommunications system having two terminals interconnected by optical fibers and active-fiber optical amplifiers. Each terminal has an optical telecommunication signal transmitter associated with an optical signal receiver which are interconnected by a protective device which causes the transmitter to be inoperative when its associated receiver does not receive an optical signal. Optical switches are provided at the downstream sides of active-fiber optical amplifiers and are controlled by detecting devices coupled to amplifier outputs, each of which detecting devices opens the associated switch in the absence of a signal having the characteristics, e.g. an alternating component, of the optical telecommunication signal whereby the protective devices are operated.

Abstract: A method and an apparatus for bidirectional optical transmission capable of bidirectional communication through a single optical transmission path are disclosed. A light traveling in one direction is modulated by a first base band signal and another light beam traveling in a second direction is modulated by a subcarrier signal which is modulated by a second base band signal for subsequent conversion into the binary digit pulse. A light receiving circuit for receiving the light traveling in said second direction is comprised of a synchronizing detection demodulator and at least a light receiver to which an electrical signal synchronizing to the subcarrier signal is applied.

Abstract: A fiber optic extender system in which messages are transferred by fiber optic lines between remotely located electronic units. The electronic units (e.g., transformer-isolated) have three signal levels: positive voltage, negative voltage, and zero voltage. Because the fiber optic system can conveniently handle only two signal levels--on and off--potentially serious communication problems are avoided by generating and transmitting a short end-of-message pulse whenever the transmitting electronic unit is at zero voltage level. This end-of-message pulse is detected at the remote electronic unit, and the line is cleared for the next message.

Abstract: A system for distributing HDTV signals from a head station to a number of customer stations includes a single head-end optical source having a frequency f.sub.0 and a modulator arranged to receive light from the single optical source. The modulator modulates the light with a sub-carrier multiplex of n channels, where n is an integer greater than 2, the n channels having frequencies f.sub.1, f.sub.2 . . . f.sub.n. The frequencies are separated in frequency-space from each other and from f.sub.0. A broadband passive branched optical network is connected to the output of the modulator and arranged to distribute the modulated signal from the head station to a plurality of customer stations each having a coherent heterodyne receiver.