Abstract: A single, normally inactive, protection channel provides protection against transponder failure in a fiber optic ring network. The protection channel is established and put into operation by a series of steps that are triggered by the detection of loss of light from one transponder by the other transponder. Each node reacts to a loss of light from another node in the same way: by rerouting incoming traffic from external sources from a working input-output interface to a protection interface, to establish a path for the protection signal, and by sending a signal enabling the two nodes to resume communication.

Abstract: An all-optical modulation format converter for converting optical data signals modulated in an on-off-keying (OOK) format to a phase-shift-keying (PSK) format. The OOK-to-PSK converter can be coupled to a delay-line interferometer to provide an all-optical wavelength converter for differential PSK (DPSK). The OOK-to-PSK converter can also be used in all-optical implementations of various functions, including, for example, exclusive-OR (XOR) logic, shift registers, and pseudo-random binary sequence (PRBS) generators.

Abstract: A method is provided for detecting an optical reflection position in an optical switching unit by using a measuring system. Multiple switching commands are provided in order to direct a test light to an input port and an output port of the optical switching unit. Status information regarding the internal path of the test light is stored in a memory, along with flags corresponding to the magnitude of reflected light generated when the test light is reflected from an abnormal position along the internal path selected. The status information is stored in the form of a reflection alarm information table where the flags are stored in association with each of the internal paths. A rearmost connection among the optical interconnections in the optical switching unit is detected as an abnormal position based on the reflection alarm information table and the interconnection control table.

Abstract: It is possible to perform reset free operation in devices having polarization state controllers by employing specific sequences of phase shifters and couplers. In particular, sequences comprising a coupler/phase shifter/coupler or phase shifter/coupler/phase shifter formed in, for example, a semiconductor substrate, e.g. silicon substrate, is used to form the polarization state controller. For example, a sequence functions as a quarter wave plate equivalent while two combined sequences function as a half wave plate. Moreover, sequences functioning as wave plates more general than quarter wave plates are advantageously employed. Control of the couplers and phase shifters of these sequences yield reset free or reset free, fully deterministic operation.

Abstract: A method for monitoring lightpaths in an optical network comprising nodes interconnected by wavelength-multiplexed links is disclosed. Each lightpath is identified by a respective optical signature. A node stores identifiers of optical signatures of lightpaths designated to traverse the node and identifiers of adjacent nodes. Each node also maintains a record of all optical signatures it detects. A command-line interface associated with a selected node tracks a selected lightpath, designated to traverse the selected node, by propagating messages in an upstream direction, a downstream direction, or both, requesting other nodes to provide information pertinent to the selected lightpath. The selected node may also send messages to all its neighboring nodes requesting each to indicated detection, or otherwise, of the selected lightpath.

Abstract: In a wavelength division multiplexed (WDM) optical communication system having optical transmitters and receivers communicating via a optical channels, the bit error rate (BER) for the optical channels is tested simultaneously by performing a BER measurement for the cascaded chain. A BER test signal is supplied from a BER tester to a first optical transmitter. The BER test signal passes through the optical channels. The last optical receiver in the cascaded chain supplies the test signal to the BER tester measure the BER. The measured BER is compared to a predetermined system BER threshold to determine if the optical channels meet their specified BER values. Each optical transmitter and receiver includes a performance monitoring circuit that monitors the quality of the BER signal supplied to the optical transmitter/receiver for identifying one or more optical channels that the measured BER exceeds a predetermined system BER threshold.

Abstract: A method for fabricating a transceiver, which simultaneously provides impedance matched transmission for radio frequency (RF) and shields against transmission losses due to parasitic effects includes identifying parasitic electromagnetic elements associated with an RF choke for a given placement on a substrate. RF lines are placed and dimensioned on the bench to form impedance matched RF lines wherein a portion of the RF lines shield the RF choke for a given bandwidth such that impedance matching and control of parasitic effects of the RF choke are simultaneously provided wherein an intermediate capacitance formed between the RF choke and the shield is sized to balance against the parasitic effects to provide a desired transmission response over a selected frequency range.

Abstract: An apparatus and method for use in an adaptive optical equalizer including, in one embodiment an optical equalizer having an input and output coupled to receive an incoming optical signal and configured to generate an output optical signal by phase modulation and/or amplitude modulation of the receive optical signal in response to electronic control signals. A photodiode is configured to receive the output optical signal and generate an representative current signal. A control signal generator is configured to generate the electronic control signals in accordance with predetermined criteria and in response to the representative current signal from the photodiode. An interferometer is connected to receive the incoming and output optical signal from the optical equalizer, the differential amplifier is configured to receive electronic versions of outputs from the interferometer for generating a difference signal and supplying the difference signal to the control signal generator.

Abstract: A method and apparatus for scheduling data burst transmission in a wavelength-division-multiplexing photonic burst-switched network is disclosed. In one embodiment, a scheduler determines a set of weighting factors at each wavelength for each of the lightpath segments among all the network nodes. These weighting factors may be used to calculate a set of coarse-grained bandwidth allocation factors, one for each potential lightpath formed from the available lightpath segments between an ingress node and an egress node. The scheduler may schedule the transmission of the data burst on one of the lightpaths that has a coarse-grained bandwidth allocation factor which indicates that it can support the requested bandwidth. The scheduler may periodically update the set of weighting factors at each wavelength for each of the lightpath segments.

Abstract: A method is provided for locating a fault in one or more optical amplifiers operating in saturation and located along an optical transmission path. The method begins by generating a coherent optical time domain reflectometry (COTDR) trace representing a backscattered and/or reflected optical power level along the transmission path and comparing the trace to a reference trace to generate a difference trace that represents a change in gain. The change in gain is assigned to at least one of the optical amplifiers based on the difference trace. The method comprises assigning the difference trace to faults in the optical amplifiers, equating the difference trace with a linear combination of difference trace vectors each arising from a fault in a different one of the optical amplifiers, and iterating to determine a coefficient value associated with each difference trace vector. Each nonzero coefficient value denotes a fault in an optical amplifier.

Abstract: A transmitter subsystem generates an optical signal which contains multiple subbands of information. The subbands have different polarizations. For example, in one approach, two or more optical transmitters generate optical signals which have different polarizations. An optical combiner optically combines the optical signals into a composite optical signal for transmission across an optical fiber. In another aspect, each optical transmitter generates an optical signal containing both a lower optical sideband and an upper optical sideband (i.e., a double sideband optical signal). An optical filter selects the upper optical sideband of one optical signal and the lower optical sideband of another optical signal to produce a composite optical signal.

Abstract: An IrDA module is coupled to a tapped inductor and makes both IrDA and remote control (RC) transmissions. The IrDA module includes a transmitter LED and a field effect transistor (FET) switch. The inductor has a first lead, a second lead and a tap. The first lead is coupled to a battery voltage, and the tap is coupled through a resistor to the LED anode. The drain of the FET switch is coupled to both the LED cathode and the second lead of the inductor. The location of the tap on the inductor is chosen such that the voltage drop across the LED when the FET switch is turned on and before the inductor saturates results in a desired IrDA LED drive current without using current-limiting resistors that can dissipate power. After the inductor saturates, the voltage drop across the LED results in a larger RC LED drive current.

Abstract: A WDM transmission system is provided which can multiplex/demultiplex and transmit wavelength division multiplexing signals, where signal lights have a different signal bandwidth, in a status without much deterioration of transmission quality. In the WDM transmission system, an optical receiver includes a demultiplexing unit which demultiplexes the wavelength division multiplexing signals and outputs the demultiplexed signal lights from a plurality of output ports, wherein each output port has transmission characteristics to be set such that the bandwidth of the transmission band where the light transmits and the bandwidth of the non-transmission band where light does not transmit are different, and the transmission band substantially matches with the signal band of the signal lights that are output from the output port out of the received wavelength division multiplexing signals.

Abstract: An RF device includes a signal layer disposed over a ground plane having radio frequency (RF) transmission lines configured and dimensioned to provide impedance matching along the RF lines. A shield is formed as a part of the RF lines and disposed below the RF choke of a DC current supply to form an intermediate capacitance between the choke and the shield to control parasitic effects.

Abstract: In optical wireless networks, light beams are transmitted over-the-air and maximum performance is achieved when light beams are aligned with corresponding light detectors. A feedback control system is created between transmitting and receiving units, wherein the receiving unit provides positional data about the light beam from the transmitting unit. The transmitting unit uses the data provided to make adjustments to its light beam. However, in order to use the positional data, the units must be operating with a common coordinate basis. A method is provided for determining the basis and generating the transformation needed to modify positional data from one unit into information that is useful for the other unit. Additionally, a method is presented for using the positional data to maintain proper alignment of the light beam.

Abstract: Gain setting of a receiving amplifier, is performed by detecting the necessity of gain setting when a receiving amplifier is turned on, requesting WDM transmission equipment in a preceding station to output ASE light; in a WDM transmission equipment of the preceding station, shutting off both passing-through light and added light, and outputting the ASE light corresponding to a predetermined number of wavelengths of signal light; in the receiving amplifier of the WDM transmission equipment in the station of interest, performing the gain setting by use of the ASE light; and on completion of the gain setting, the WDM transmission equipment of the station of interest, requesting the WDM transmission eouipment of the preceding station to halt the ASE light output, and the WDM transmission equipment of the preceding station, halting the ASE light output upon receiving the request and switching the output to an optical signal output.

Abstract: An optical receiver including an optical divider to divide a signal light from an optical transmission line into two portions, a first and a second dispersion compensators, each dispersion compensator having variable dispersion compensation to compensate chromatic dispersions of each of the two portions of signal light output from the optical divider, and a data demodulator to demodulate a data carried by a signal light output from the first dispersion compensator. The optical receiver further includes an optical autocorrelator to operate on a signal light output from the second dispersion compensator and a controller to control the second dispersion compensator to increase autocorrelation of the optical autocorrelator, and to control the first dispersion compensator according to the result of said controlling the second dispersion compensator.

Abstract: A single, normally inactive, protection ring, provides protection against a working channel failure in a fiber optic ring network. The protection channel is established and put into operation by a series of steps that are triggered by the detection of signal degradation or loss of light from one transponder by the other transponder. Each node reacts to a failure of another node in substantially the same way. Incoming traffic from external sources is rerouted from a working input-output interface to a protection interface, to establish a path for the protection signal. Signals are sent between nodes enabling the two nodes to resume communication. Only the portion of the protection ring between nodes is placed into service.

Abstract: A bi-directional (BiDi) electrical to optical converter (transceiver) module is described that contains means for communicating in a full duplex fashion over one fiber. Furthermore, an automatic fail-over capability is included which allows redundancy to be build in to the transceiver. In one configuration, a BiDi transceiver module contains two lasers at different wavelengths and a means for establishing which wavelength to communicate with. An example of an application for the described invention is a storage area network application which requires redundant links and are currently bound by the number of fibers connecting to the front panels of switches.

Abstract: A router comprising an interface module (IM), having an optical path and an electrical path and a speed sensor coupled between an input of the router and an input of the IM. The speed sensor is adapted to receive a packet and detect a speed of the IM connection and in response to the speed of the IM connection being above a threshold value, the speed sensor provides the packet to the optical path of the IM and in response to the relative speed being below the threshold value, the speed sensor provides the packet to the electrical path of the IM.