Abstract: A method of determining end points for an optical channel in an optical network to off-load traffic from a target optical link is provided. The method includes the steps of identifying ingress network nodes sourcing traffic through the target optical link, and determining an average ingress bandwidth sourced by the ingress network nodes. Thereafter, the method includes the steps of identifying egress network nodes sinking traffic from the target optical link, and determining an average egress bandwidth sunk by the egress network nodes. The optical channel start point candidates are identified to include ingress network nodes sourcing more traffic than the average ingress bandwidth, and the optical channel end point candidates are identified to include egress network nodes sinking more traffic than the average egress bandwidth.

Abstract: A dispersion compensator provides dispersion compensation to a WDM optical signal having a plurality of channels located at different wavelengths and traveling in an optical transmission path. The dispersion compensator includes an optical splitter adapted to receive the WDM optical signal. The optical splitter has first and second output ports such that a subset of the plurality of channels are directed along the first output port and remaining ones of the plurality of channels are directed along the second output port. A dispersion compensating element is coupled to the first output port and a multiplexing element having a first input port is coupled to second output port of the optical splitter. The multiplexing element also has a second input port coupled to the dispersion compensating element and an output port on which the subset of channels and the remaining ones of the channels are recombined.

Abstract: An embodiment includes a polarization beam splitter and a feedback unit, preferably having an autocorrelator, a processing unit and a polarization controller. Polarized splitter separates the lower-speed tributary signals out of the higher-speed optical signal based upon a polarization relationship (e.g., orthogonal) between the tributary signals. The feedback unit, typically an autocorrelator and a polarization adjustment device, adjusts the higher-speed signal's state of polarization based upon an autocorrelation value of one of the lower-speed tributary signals. The autocorrelation value of one of the lower-speed tributary signals is provided to the polarization adjustment device, which typically includes a processing unit and a polarization controller. The polarization adjustment device adjusts the higher-speed signal's polarization state based upon the autocorrelation extinction ratio value.

Abstract: A passive optical network is provided that integrates signals carrying broadcast CATV services into a FTTH/C network that also provides high-speed Internet access and telephony. Essentially all residential telecommunications services are provided in a single network, based on a single fiber and a single simple transceiver in an optical network unit. Multiple services (e.g., analog video, digital video, cable-modem based Internet access) are multiplexed using separate rf subcarriers (subcarrier multiplexing or SCM) and the delivered signals are compatible with existing consumer appliances (e.g., TVs, VCRs, cable modems, etc.).

Abstract: A transmission system includes a plurality of remote units in communication with a station unit, wherein communication is with fixed length cells in the upward direction from the remote units to the station unit by a TDMA system, and in the downward direction from the station unit to the remote units by a TDM system. The station unit is adapted to detect whether one of the plurality of remote units is in a standby state and is responsive to a detection of one of the plurality of the remote units being in a standby state to allocate bands of communication from the remote unit in the standby state to a remote unit in a normal state.

Abstract: This invention provides method and apparatus for ancillary data in a wavelength division multiplexed (WDM) system. According to the invention, a low bit rate channel is provided over a amplitude modulated sub-carrier that is in turn used to amplitude intensity modulate an optical data signal that is output from a transmitter in the network. Data carried by the low bit rate channel can by used by another network element (NE) to determine the identity of the channel source, thereby allowing the NE to verify its connectivity to that source via the network. This invention is particularly useful in metropolitan optical networks (MON) where inexpensive methods of determining network connectivity are required.

Abstract: A point-to-multipoint bi-directional wide area telecommunications network employing atmospheric optical communication. The network comprises a primary transceiver unit, a plurality of subscriber transceiver units and an optical router. The primary transceiver unit may send data destined for the subscriber transceiver units through the optical router, and the subscriber transceiver units may send data destined for the primary transceiver unit through the optical router. The primary transceiver unit and optical router communicate by means of light beams which are transmitted through the atmosphere. Similarly, the optical router and the subscriber transceiver units communicate by means of light beams which are transmitted through the atmosphere.

Abstract: The present invention provides an optical parallel transmission system which can achieve reduction of the processing time without adding many processing functions. A pattern data adder adds, to transmission data, pattern data determined from the transmission data so that the transmission data per one bit becomes data having a form close to a repetition of “1”, “0”, and optical parallel transmission by AC coupling is realized thereby.

Abstract: A method and apparatus performing fault management in an optical communications system including a polarization mode dispersion (PMD) compensator. The method and apparatus utilizes a controller receiving notifications indicative of PMD in the system, as well as at least one indicator from a system device providing an indication of an attribute of the communication system. Such system devices include a receiver providing a Q factor and a bit error rate (BER) of an optical signal, and a signal-to-noise ratio meter providing an SNR of the optical signal. The method intelligently provides fault management by correlating the PMD notifications and system indicators to distinguish between fiber failure, PMD-related degradations, and failure of monitoring equipment itself.

Abstract: A digital optical transmission apparatus includes a modulation portion for modulating data to be transmitted in an ASK modulation method, and an E/O modulation portion for converting an electrical signal output from the modulation portion into an optical signal having a base band component with a constant DC level. DC-biased or FSK-biased may be employed as a method of making constant the DC level of the base band component.

Abstract: An optical apparatus comprises a 2D-spatial light modulator, an input-ring array, an output-ring array and an optical interconnect. The 2D-spatial light modulator produces a modulated light beam for each of a plurality of processing elements. The modulated light beams have a plurality of light wavelengths. An input-ring array receives the plurality of data modulated light beams. An output-ring array outputs a light beam to each processing element. An optical interconnect transfers light from the input-ring array to the output ring array and uniquely rotates each wavelength of the transferred light.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: An optical packet header processing apparatus for processing a header of an optical packet expressing an address of a destination node to control a switching operation of an optical packet switch. The optical packet header processing apparatus comprises a beam splitter for splitting the optical packet header into a predetermined number of optical packet header elements, and a plurality of time interval detectors. Each of the time interval detectors receives a corresponding one of the optical packet header elements from the beam splitter and outputs a detect optical pulse if a pair of optical pulses having a predetermined time interval therebetween are present in the received optical packet header element. A plurality of optical pulse detectors are adapted to convert the detect optical pulses from the time interval detectors into electrical signals and transfer the converted electrical signals to the optical packet switch, respectively.

Abstract: An optical wavelength add/drop multiplexer (WADM) is configured to add or drop two or more signals each associated with one of a plurality of channels in a wavelength division multiplexed (WDM) signal. The WADM comprises an optical circulator that is optically coupled at one port to two or more serially interconnected fiber Bragg gratings (FBGs), and is optically coupled at another port to a thin film filter including two or more serially interconnected thin film filter elements. Each of the two or more FBGs is matched with a thin film filter element, both arranged to be responsive to signals associated with one of the plurality of channels. Bandwidth and dispersion properties for the FBGs are selected to permit operation of the WADM at two distinct signal data rates.

Abstract: A point-to-multipoint bi-directional wide area telecommunications network employing atmospheric optical communication. The network comprises a primary transceiver unit, a plurality of subscriber transceiver units and an optical router. The primary transceiver unit may send data destined for the subscriber transceiver units through the optical router, and the subscriber transceiver units may send data destined for the primary transceiver unit through the optical router. The primary transceiver unit and optical router communicate by means of light beams which are transmitted through the atmosphere. Similarly, the optical router and the subscriber transceiver units communicate by means of light beams which are transmitted through the atmosphere.

Abstract: A method and apparatus is provided that yields improved performance of both single channel and WDM long-distance optical transmission systems by synchronously modulating of the transmitted signal's amplitude. An amplitude modulator receives an optical signal onto which data has been modulated at a predetermined frequency. The modulator re-modulates the amplitude of the optical signal in a continues fashion with a waveform that is periodic, whose fundamental frequency is equal to the same predetermined frequency at which the data is modulated onto the optical signal. The resulting signal (which is neither a pure NRZ or RZ signal) is more tolerant to the distortions usually found in lightwave transmission systems, thus giving superior transmission performance.

Abstract: An optical repeater monitoring system, according to the invention, comprises an oscillating source, a reference signal transmitter for transmitting a reference signal of a predetermined frequency generated from an output of the oscillating source to a first optical fiber, and an optical repeater. The optical repeater has a first photodetector for converting light from the first optical fiber into an electrical signal, a reference signal extractor for extracting a component of the reference signal from an output of the first photodetector, a carrier generator for generating a carrier from an output of the reference signal extractor, a monitor signal modulator for modulating the carrier generated by the carrier generator with a monitor signal showing a operating state of the optical repeater, a transmitter for transmitting an output of the monitor signal modulator to a second optical fiber.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: The present invention relates to a routing address encoder, a routing controller, and a routing switch, which decrease the number and the length of optical splitting and optical delay line at optical routing circuits in optical communication network. A routing address encoder in accordance with an embodiment of the present invention includes a pulse generator, an external modulator, an optical address generator, an address selection signal generator, an optical switch, and optical OR gate means. An optical routing circuit for decoding optical routing information received from optical communication network and routing optical signals on the basis of routing address is provided. An optical routing circuit includes an optical splitter, a routing controller, and a routing switch.

Abstract: M wavelength separating sections receive multiplexed optical signals each having N kinds of wavelengths different. Each of the multiplexed optical signals are separated into N optical signals. M relays conduct optical reproduction and relay to convert each of the N optical signals into electric signals and then produce optical signals modulated with desired optical wavelengths. A refill section mutually refills M sets of the reproduced and relayed optical signals. A focusing section focuses the M sets of optical signals refilled in the refill section. A light source supplies input lights having desired wavelengths, which lights are modulated in the relays. The light source includes N light sources outputting N kinds of optical wavelengths. A multiplexer/brancher multiplexes the lights from the N light sources to produce a multiplexed light and branches the multiplexed light into M×N distributed lights. M wavelength filters distribuitively receive N distributed lights of the M×N distributed lights.