Abstract: A method and system for detecting optical faults by tapping a portion of a data signal from along a fiber network link at an optical switching site or node. The tapped data signal is evaluated to determine whether an optical fault exists along the fiber link. In this way, optical faults such as a fiber failure, cable cut, or nodal LTE failure occurring within a network path, are isolated to a specific fiber span or link. Network switch controllers can then take full advantage of optical switches provided between spans in an all-optical core network to restore end-to-end path communication. In one embodiment, a presence detector simply evaluates the magnitude of the tapped signal to determine an optical fault. In a second embodiment, a protocol analyzer evaluates selected bits or fields of the protocol used in the tapped data signal to determine an optical fault. Finally, in a third embodiment, a sub-carrier modulation signal is added to the high rate data signal prior to transport over the link.

Abstract: A high speed optical receiver for receiving a substantially diminished optical signal. An optical amplifier amplifies the diminished optical signal at least several db and an ultra narrow-band filter filters the noise generated in the optical amplifier to produce a filtered amplified optical signal which is detected by a fast response photo detector. In a preferred embodiment the optical amplifier is a semiconductor laser amplifier. In this embodiment a Faraday filter provides the ultra narrow-band filtering, virtually eliminating the noise produced by the amplifier. Transmitters are described for transmitting information at a wavelength tuned to the ultra narrow-band filters.

Abstract: A laser bias preconditioning methodology is provided, and an implementation of that methodology, that improves the carrier-to-noise ratio of analog CATV signals sent over an optical transmission medium. The bias preconditioning methodology causes the laser bias current to be continuously varied to track an envelope of the carrier signal.

Abstract: An ultra-wideband signal processor, such as that employed for processing narrow time domain radar return pulses, includes a coherent acousto-optic Bragg cell channelizer having a plurality of IF outputs from which a plurality of IF output signals respectively representative of energy content of respectively different frequency portions of the RF input signal are derived. A summing circuit is coupled to sum the IF output signals to produce a summation signal representative of their average energy content. This average energy signal is compared with a threshold to determine if the input signal is a valid RF signal. A delay circuit delays a selected one of the IF output channels by a time sufficient to accommodate summation of the channelizer outputs and determining whether a valid RF signal is present. A digital signal processor processes the delayed selected output signal in response to the summation signal exceeding the threshold.

Abstract: A method and apparatus for optimizing dispersion in an optical fiber transmission line. The method and apparatus (a) determine an optimum amount of total dispersion of an optical transmission line corresponding to a power level of an optical signal transmitted through the optical transmission line; (b) control dispersion of the optical transmission line so that the total dispersion up to a specific point along the optical transmission line becomes approximately zero; and (c) add dispersion to the optical transmission line downstream of the specific point, to obtain the determined optimum amount of total dispersion. The control of dispersion in (b), above, can be performed in several different manners. For example, the control of dispersion can include (i) detecting the intensity of a specific frequency component of the optical signal, the optical signal having an intensity v.

Abstract: A method of reconfiguring a multi-wavelength communication network. The transition includes determining the union of the old and new topologies. During at least the start of the transition, the network supports the union topology. New connections are connected according to the new topology, and the old topology, as its connections expire, is gradually removed. In allocating wavelengths to a new topology, two algorithms are developed which assign wavelengths which do not color clash with the wavelength assignments of the old topology.

Abstract: A digital optical telecommunication method including the steps of: generating a digital modulated optical signal in an optical transmitting station, which signal corresponds to a first electric input signal carrying a piece of information; feeding the modulated optical signal to an optical-fiber line; receiving the modulated optical signal transmitted from the optical-fiber line at an optical receiving station, converting it to an electric form and thereat generating a second digital electric signal; wherein the modulated optical signal is coded in a sequence of elementary information units at a first frequency and wherein the step of generating a second digital electric signal comprises detecting in said converted signal, an electric signal having a second frequency higher than the first frequency and recognizing in said detected signal, the phase of an electric signal at the first frequency by comparing a received sequence of elementary information units with at least one reference sequence and verifying th

Abstract: The apparatus includes a first housing (10) defining a first chamber (26), the first chamber sized to enclose an electronic device. The first housing has an inner surface (22) and an outer surface (24), and at least a portion of the first housing is transparent. A light-generating device (14) is disposed at least in part between the inner surface and the outer surface of the transparent portion of the first housing. The light-generating device has a first end and a second end. The first end is responsive to electrical signals (18) and the second end is responsive to optical signals (20). When a first electronic device (45) is disposed in the first chamber, the first electronic device transmits electrical signals to the first end, the second end translates the electrical signals to optical signals and transmits the optical signals through the outer surface.

Abstract: A dispersion-tapered fiber for use in a soliton transmission system having lumped amplifiers to substantially reduce loss associated with pseudo phase matching and to relax the limitations on minimum allowable channel spacing caused by cross-phase modulation. The dispersion tapered fiber has a dispersion tapered either continuously or in steps, in conformity with the fiber loss curve.

Abstract: A computer system adapted to receive and interpret signals from a remote control. The signals received from the remote control are interpreted and transformed into signals equivalent to those produced by a computer keyboard.

Abstract: An optical interconnect for use with SIMD processors, including holographic-optical elements, dove prisms, beamsplitters and a processor. Laser diodes, with each operating at a different wavelength, generate coherent-light beams at different wavelengths. A fiber combiner, an optical fiber and a fiber splitter are connected to divide output light from the laser diodes into equal path lengths. The output light is modulated by data from a respective SIMD processor. The output light forms an input ring at an input plane. Each holographic-optical element reflects only one wavelength of the output light. Dove prisms perform certain fixed interconnections. Beamsplitters reflect the light from the selected optical channel to an output-ring array.

Abstract: A method and system for detecting optical signal degradation or loss within the optical domain of a fiber network. Optical cross-connect switches (OCCS) are provided at network nodes. Optical data traffic is conducted between nodes via a fiber link. The fiber link extends between respective ports of the optical cross-connect switches at each network node. Dedicated signals for detecting faults are introduced and removed within the optical domain of the fiber communication network. In one embodiment, transmitter/receiver units are coupled directly to the fiber link for broadcasting optical signals for fault detection. In another embodiment, transmitter/receiver units are coupled to the fiber link through one or more dedicated ports within optical cross-connect switches (OCCS) at network nodes. Optical signals for fault detection are then broadcast or switched through working and/or spare fibers. Distinctive optical fault detection signals are used when the signals are broadcast or switched over working fibers.

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: A verification system for a switch or other element in a digital transmission system includes a sample extraction means for tapping a input to the switch, and a similar means for tapping an output of the switch. Analogue features of the signal passing through the switch are tapped off and compared by pattern matching without demultiplexing digital data from the signal passing through the switch. The result of the match can be used to verify the switch has switched correctly, or to monitor other parameters such as cross-talk.

Abstract: A switch in an optical network unit selectively couples line side ports of the line cards of the unit to individual line circuits in drop cable wiring extending to the customer premises served by the unit. The switchable optical network unit (SONU) permits rapid automated upgrades of service. For example, automatic switching of a line circuit to a line card offering an upgraded service together with automatic provisioning of the SONU to activate service through that line card provides the new upgraded service over the existing line circuit, without requiring a technician to install a new line card or manually connect the line card to the line circuit. If the drop cable to the customer premises includes a primary line circuit and an auxiliary line circuit, the line port can be switched over from the primary line circuit to the auxiliary line circuit to automatically restore service in the event of a failure of the primary line circuit.

Abstract: In an electroabsorption optical intensity modulator, a semiconductor buffer, a first semiconductor cladding layer, a semiconductor optical absorption layer, a second semiconductor cladding layer and a semiconductor cap layer are formed on a semiconductor substrate. Also, a first electrode is formed on the second semiconductor cap layer, and a second electrode is formed on a second surface of the semiconductor substrate. The semiconductor optical absorption layer includes a first semiconductor optical absorption layer element having a first absorption edge wavelength and a second semiconductor optical absorption layer element having a second absorption edge wavelength different from the first absorption edge wavelength.

Abstract: Stackable modules using infrared (IR) radiation for communication. Each module includes a housing with upper and lower holes and IR transceivers aligned with the holes. One of the two IR transceivers or transceiver sets detects IR communications through a lower hole and transmits through an upper hole, and the other detects IR communications through an upper hole and transmits through a lower hole. In this manner, the stackable module uses IR radiation to communicate with similar modules both above and below the module. The module further includes communication logic coupled to the transceivers to control communications between the transceivers of different modules. The module preferably includes a network device operating according to any desired network protocol. A stack network system includes a chassis with several slots, where one or more stackable modules are removably plugged into the slots of the chassis. Management may be distributed among the modules or centralized.

Abstract: A wavelength division multiplexing light transmitting system which can monitor its transmission line. In which, one light among the signal lights to be wavelength multiplexed is defined as an optical fiber transmission line monitor light. A transmitter multiplexes and transmits the monitor light with the other signal lights. These lights are attenuated and introduced to the other transmission line at return circuits 12. A receiver branches the returned lights, selects the monitor light and detects a condition of the transmission line by correlation processing. The system extremely improves a SNR and a detection time of the monitor signal.

Abstract: To provide a microoptical system for free-space optical interconnection capable of relaxing the arrangement accuracy of a light source and a photodetector. A point light source and a photodetector are interconnected each other by first and second imaging lenses and focused Gaussian beams. In this case, the point light source, first imaging lens, second imaging lens, and photodetector are positioned so that the effective beam radius .omega..sub.2 of a focused Gaussian beam on the first interconnecting lens is larger than the effective beam radius .omega..sub.4 of a focused Gaussian beam on the second imaging lens.

Abstract: Described are novel passenger conveyance vehicles and passenger transit systems which are configured to transmit signals which, when properly received and converted, provide intelligible non-visual communication to current and/or prospective passengers.