Abstract: An optical transport system (OTS) having a plurality of optical transponders (OTs) connected via one or more optical links and adapted to communicate with one another using respective rate-adaptive forward-error-correction (FEC) codes. In one embodiment, the OTS has a rate control unit (RCU) adapted to configure the OTs to dynamically adjust the rates of the FEC codes based on an estimated performance margin for each link between two respective communicating OTs to optimize the overall capacity of the OTS while maintaining an adequate, but not excessive, overall system margin.

Abstract: An optical transport system (OTS) having a plurality of optical transponders (OTs) connected via one or more optical links and adapted to communicate with one another using respective rate-adaptive forward-error-correction (FEC) codes. In one embodiment, the OTS has a rate control unit (RCU) adapted to configure the OTs to dynamically adjust the rates of the FEC codes based on an estimated performance margin for each link between two respective communicating OTs to optimize the overall capacity of the OTS while maintaining an adequate, but not excessive, overall system margin.

Abstract: Apparatus for creating a communication signal, comprising a modulator adapted to: modulate a first and a second beam of continuous wave electromagnetic radiation with a source signal, assemble modulated portions of the first and second beams into a first electromagnetic radiation signal of interposed regular and alternate data bit sequences comprising asserted non return to zero coded data bits, each of the data bit sequences being interposed by unasserted data bits, in which mutually adjacent asserted data bits are conjoined, and assemble modulated portions of the first and second beams into a second electromagnetic radiation signal of interposed regular and alternate data bar bit sequences comprising asserted non return to zero coded data bar bits representing the unasserted data bits, each of the data bar bit sequences being interposed by unasserted data bar bits representing the asserted data bits, in which mutually adjacent asserted data bar bits are conjoined.

Abstract: A dual-output Mach-Zehnder modulator (MZM2) and configurations of optical transmitters based on the MZM2 which obviate the optical splitter that is typically used to provide keep-alive functionality in redundantly-connected, protected optical networks, SONET add-drop multiplexers, and optical IP routers. The configurations provide equivalent keep-alive utility at a reduced system cost relative to the prior art. The configurations also support enhanced Operations, Administration, Maintenance, and Provisioning (OAM&P) functionality at little to no additional cost relative to the prior art. Instead of being a direct copy of the service signal, the keep-alive of this configuration is an inverted version of the service signal. This inverted version of the service signal is supported at a client by utilization of means for detecting and righting the inverted signal.

Abstract: In a telecommunications network, such as an optical mesh network, satisfying a demand from a start node to an end node, the network is automatically provisioned from a service path to a restoration path after a failure occurs in the service path. Each affected node in the network eventually receives an indication of the occurrence of the failure in the service path. If the node is an intermediate node of the service path, then the node transmits a failure message to its next node along the service path. If the node is the end node of the service path, then the node transmits a restore message to its previous node along the restoration path. If the node is an intermediate node of the restoration path, then the node transmits a restore message to its previous node along the restoration path. In addition, the node reconfigures its cross-connect for the transition from the service path to the restoration path.

Abstract: In a telecommunications network, such as an optical mesh network, satisfying a demand from a start node to an end node, the network is automatically provisioned from a service path to a restoration path after a failure occurs in the service path. Each affected node in the network eventually receives an indication of the occurrence of the failure in the service path. If the node is an intermediate node of the service path, then the node transmits a failure message to its next node along the service path. If the node is the end node of the service path, then the node transmits a restore message to its previous node along the restoration path. If the node is an intermediate node of the restoration path, then the node transmits a restore message to its previous node along the restoration path. In addition, the node reconfigures its cross-connect for the transition from the service path to the restoration path.

Abstract: A dual-output Mach-Zehnder modulator (MZM2) and configurations of optical transmitters based on the MZM2 which obviate the optical splitter that is typically used to provide keep-alive functionality in redundantly-connected, protected optical networks, SONET add-drop multiplexers, and optical IP routers. The configurations provide equivalent keep-alive utility at a reduced system cost relative to the prior art. The configurations also support enhanced Operations, Administration, Maintenance, and Provisioning (OAM&P) functionality at little to no additional cost relative to the prior art. Instead of being a direct copy of the service signal, the keep-alive of this configuration is an inverted version of the service signal. This inverted version of the service signal is supported at a client by utilization of means for detecting and righting the inverted signal.

Abstract: A method and apparatus for deriving insertion losses for connections in a single-stage optical cross-connect. The optical cross-connect comprises a number (N) of input ports, a number (M) of output ports and an on-board controller. A memory is provided on the on-board controller for storing N loss parameters for the N input ports and M loss parameters for the M output ports. A modeled insertion loss for a connection between any input port and any output port can be derived from the loss parameters associated with the input and output ports.

Abstract: In a telecommunications network, such as an optical mesh network, at a node along a service path satisfying a demand from a start node to an end node, the node can detect a failure in the service path by any of three different ways: (a) by monitoring incoming payload signals from its previous node along the service path for a loss-of-signal (LOS) condition; (b) by monitoring the incoming payload signals from its previous node along the service path for an in-band alarm indication signal; and (c) by monitoring an out-of-band signaling channel for a failure message transmitted from its previous node along the service path. The node then determines appropriate actions as part of a distributed restoration procedure depending on whether the node is an intermediate node or the end node along the service path. If the node is an intermediate node, then the node passes the out-of-band failure message to its next node along the service path.

Abstract: A light source for generating many precisely spaced wavelength channels, based on the periodic modulation of light. CW light is periodically amplitude modulated and then coupled to a non-linear fiber where it undergoes additional modulation by the process of self-phase modulation or other non-linear effects. In a general embodiment of the multi-wavelength source (MWS), an optical modulator driven by a periodic electromagnetic signal imposes periodic amplitude modulation on light from a single longitudinal mode CW laser. The light is then coupled to a non-linear medium with an intensity dependent refractive index where it generates higher order spectral sidebands by the process of self-phase modulation and/or other non-linear effects. The frequency spacing between the spectral components is equal to the repetition rate of the modulation. The shape of the spectrum (i.e.

Abstract: An optical device having a first substrate having a fast optical axis and a slow optical axis and a first end and a second substrate having a fast optical axis and a slow optical axis and a second end, the second end is positioned adjacent to the first end such that the fast optical axis of the first substrate is coupled to the slow optical axis of the second substrate and the slow optical axis of the first substrate is coupled to the fast optical axis of the second substrate, thereby permitting an optical signal to pass between the first and second substrates. The first substrate and the second substrate have substantially equal length to thereby substantially eliminate polarization dispersion.

Abstract: Spectral broadening over a large range using PM is achieved by a lightwave source without the need for a large phase modulation index and without expending a large amount of modulator RF drive power. In this lightwave source, a laser output signal is externally phase modulated by one or more modulation signals. The phase modulation employs one or more frequency drive signals (i.e., the modulation signals) each of whose amplitude is judiciously selected to produce an output spectrum having substantially equal spectral components over a predetermined range of frequencies. The predetermined frequency range is centered about the source frequency for the laser and resembles a comb. Each frequency drive signal is also selected to have a frequency (or frequency spacing from other drive signals) so that adjacent spectral components in the output spectrum of the modulated signal are produced with a frequency spacing which exceeds the SBS interaction bandwidth at the transmission wavelength of interest.

Abstract: An optical pulse generator for producing a soliton pulse train having a modulator which amplitude and phase modulates an optical frequency output of a continuous optical wave source. The modulator is driven by first and second harmonically related continuous sinusoidal waves from first and second CW voltage sources and the generator includes a pulse compression means for producing at the output of the generator a soliton pulse train.

Abstract: An interferometric modulator comprising a substrate of titanium-doped lithium niobate (Ti:LiNbO.sub.3) having top and bottom surfaces and a waveguide formed in the top surface is disclosed. A conductive layer is formed on the bottom surface of the substrate and electrically coupled to a top-surface ground plane or simply to ground potential. The bottom surface conductive layer functions to thermally stabilize the modulator during operation.

Abstract: External modulation is accomplished in a dual waveguide device wherein substantially identical input optical beams are supplied to the waveguides and wherein each waveguide through its electrode is subject to individual, mutually exclusive control. Modulation signals are applied to each waveguide via its separate electrode. Control signals are applied to each waveguide for adjusting the modulation chirp parameter to a desired fixed, non-zero value. Typically, the desired value of the chirp parameter is one which provides the lowest fiber dispersion penalty for the system. Modulated lightwave signals emerging from the waveguides are combined to form a single output signal suitable for transmission over an optical fiber. In one embodiment, Mach-Zehnder interferometer having separately controllable waveguides has its input coupled to a CW laser. Both III-V semiconductor and Ti:LiNbO.sub.

Abstract: It has been determined that optical fibers possess a small amount of nonlinearity and, therefore, they are not exactly linear waveguides. This small amount of nonlinearity enables certain special pulse shapes to establish themselves and travel long distances without changing shape. These special pulse shapes are called solitons. This invention relates to a device for generating solitons by amplitude modulating an optical signal with separate in-phase electrical signals of different harmonically related frequencies. Specifically, an amplitude modulator such as a Y junction Mach-Zehnder interferometer has multiple sets of distributed electrodes. The interferometer has a set of electrodes for each electrical signal of a specific frequency. Thus, if three separate signals of harmonically related frequencies are used to amplitude modulate an optical signal, then the interferometer has three sets of electrodes located between the Y junctions of the Mach-Zehnder interferometer.

Abstract: Briefly, in the invention a photodetector and an optical amplifier are integrated in the same semiconductor chip. The optical amplifier and the photodetector are positioned side-by-side on the same chip. A portion of the electromagnetic energy carried in the evanescent tail of the optical mode is detected by the photodetector for monitoring the average output power of the optical amplifier. Current confinement and lateral index guiding can be provided by Fe or Ti doped semi-insulating layers of InP. The side-by-side arrangement enables the detector to monitor the output power of the optical amplifier without degrading the output power of the optical amplifier.

Abstract: The device here disclosed comprises an optical amplifier coupled to direct optical energy into a passive waveguide for transmission through the waveguide to its other end. A photodetector, positioned relative to the passive waveguide, detects the presence of optical energy in the passive waveguide. The photodetector in the structure illustrated is positioned downstream from the optical amplifier and spatially positioned with respect to the optical amplifier to receive optical energy only from the waveguide. The photodetector does not receive optical energy directly from the optical amplifier. A small fraction of the optical energy carried by the passive waveguide is received and detected by the photodetector.

Abstract: Disclosed is a time division multiplexed optical communication system that is capable of operation at relatively high bit rates and that is relatively stable and immune to crosstalk and noise. The system comprises receiver means wherein the timing signal for demultiplexing is derived from the fully multiplexed optical pulse stream by means that comprise a narrow band receiver and timing means that produce a lower-frequency timing signal from the output of the narrow band receiver. The timing signal is used to drive one or more optical switches. In one embodiment of the invention the receiver means have a binary-tree architecture and the timing signals are substantially sinusoidal. In another embodiment the receiver means have a linear-bus architecture and the timing signals are pulse-like.

Abstract: An optical intersection with reduced transmission loss is described. An embodiment of the inventive interconnection comprises two intersecting waveguides. According to the teachings of the invention, deleterious asymmetric field distortions in the waveguides, associated with the presence of the adjacent waveguides, are reduced by, for example, changing the width of the intersection region, and the widths of the waveguides as they approach the intersection region.