Abstract: A technique for routing data within an optical network having a plurality of network nodes is disclosed. In one embodiment, the technique is realized by receiving data at a first network node via a first optical signal having a first wavelength. The first wavelength corresponds to a first optical frequency, and the first optical frequency is mapped to a first binary representation. The first binary representation is divided into a first plurality of fields, wherein at least one of the first plurality of fields corresponds to a routing label in a first label stack. A top routing label in the first label stack indicates a second network node. Based at least partially upon the top routing label, the data is transmitted from the first network node to the second network node via a second optical signal having a second wavelength. The first wavelength may be either the same as or different from the second wavelength.

Abstract: For suppressing intra-channel four wave mixing in a time division multiplexing (TDM) system, where N synchronous data streams, each having a reduced data pulse width within a bit slot timing interval, from parallel to serial form, are converted for optically bit interleaving the N synchronous data streams into the optical communication link at a nominal bit slot delay between sequential N synchronous data streams related to the bit slot timing interval to provide a serial data sequence of short optical pulses having an equal bit slot delay between sequential pulses, a sequential bit slot delay is varied between two of the short optical pulses to provide an unequal bit slot delay between sequential pulses within the serial data sequence of short optical pulses for suppression of undesired intra-channel four-wave mixing pulses among the pulses and thereby, improvement of transmission performance.

Abstract: A photonic switching device for switching without contention data in the form of optical packets includes a space switching matrix with a plurality of input ports and a plurality of output ports. A unit external to the space switching matrix includes a buffer memory common to all the output ports of the matrix. Each of the output ports provides access to the buffer memory via a space switching stage consisting of switches having a 1-to-2 switching function.

Abstract: One of optical packets x copied by an optical copying mechanism 11 is converted into an electric packet by an optic/electric converting mechanism 13. An address information extracting mechanism 14 extracts address information from a header of the packet converted into the electric packet. A control light generating mechanism 15 generates a control light based on the extracted address information. The other of the copied optical packets x is delayed by an optical delaying mechanism 12 for a predetermined time, and entered to a third nonlinear optical effect device 1b. The third nonlinear optical effect device 1b switches a route of the optical packet x based on the control light. The optical packet x is outputted through an optic/electric converting mechanism 1h0, a buffer 1i0, a multiplexing mechanism 1j, and an electric/optic converting mechanism 1k.

Abstract: A novel integrated multiple-rate optical time division multiplexing (OTDM) module is disclosed. An integrated set of modulators generates optical RZ signal streams which are then time-delayed by a set of integrated optical delay switching and combining arrays and interleaved to produce an OTDM signal. The integrated optical delay switching and combining arrays are adapted to be controllably set to various delays to facilitate interleaving of many possible bit-rates. Such an approach alleviates stability problems offered by conventional fiber-based OTDM technology, increases flexibility, aids in reducing the size, complexity, and cost. Furthermore, the OTDM chip of the present invention offers fine tuning capabilities thereby allowing for slight adjustments in the interleaving of optical signal streams if needed. The present invention also provides for the integration of an optical pulse source chip and a multiple-rate OTDM chip onto a single substrate or platform using hybrid packaging technology.

Abstract: Packets conveying data are received by a router via input ports which impose on them optical carrier waves whose wavelengths correspond to the ports. Respective time-delays are applied to the packets and they are broadcast to spatial selectors that transmit them to spectral selectors. Amplifiers are distributed over the paths of the packets and the paths are organized in such a manner as to limit the number of semiconductor optical switches in the selectors and to minimize noise and optical crosstalk affecting the packets.

Abstract: A protection arrangement for an optical switching system includes protection switching for switch planes in the optical core and for ports in the tributary cards. For a multiple layer switch core protection is also provided between layers. A first layer is for switching optical channels. The protection switches used may be 1×N, 2×N or 3×N MEMS optical switches. The 1×N MEMS provides for protection switching. The 2×N MEMS provides protection switching and testing capability. The 3×N MEMS provides for protection switching, testing and backup of the protection switching. Application of these protection switches is shown in lambda plane switch cores, multiple layer switch cores and combined switch cores.

Abstract: A chromatic dispersion compensator comprises a beam delay element, such as one or more Gires-Tournois etalon (GTEs); a beam director, such as a polarizing beam splitter (PBS), a prism polarizer, a dielectric polarizer or a crystal polarizer; and a polarization changer, such as one or more quarter-wave plates. The beam director directs an inbound optical beam based on its polarization toward the beam delay element whereat a first unit of group delay is induced. The optical beam traverses the beam delay element and enters a polarization changer whereat the optical beam obtains a new polarization. The optical beam traverses the polarization changer and re-enters the beam director whereupon a path change is induced on the optical beam based on its new polarization and the optical beam is redirected toward the beam delay element whereat a second unit of group delay is induced.

Abstract: Methods and apparatus are contemplated for multiplexing and de-multiplexing modulated optical signals using dispersion. Optical signals comprising a wavelength-multiplexed plurality of modulated spectra may be additionally multiplexed and de-multiplexed using dispersion. Dispersion multiplexing may be used in the simultaneous two-way propagation of optical signals over a waveguide.

Abstract: A light-controlled light modulator can achieve high-speed, low-loss wavelength conversion. Continuous light with a wavelength ?j is launched into an MMI coupler via a port, and is split into two parts by the MMI coupler, which are led to a loop-type interferometer. In the loop-type interferometer, the two parts travel separately around the loop as clockwise traveling light and counterclockwise traveling light, are combined by the MMI coupler again via a filter-equipped phase modulator, thereby being emitted to the port. In this state, signal light ?i(s) with a wavelength ?i is launched into the filter-equipped phase modulator via a port. Even when the wavelength ?i of the signal light ?i(s) is equal to the wavelength ?j of the wavelength converted output light, the wavelength conversion can be achieved with preventing noise from being mixed into the output light emitted from a port.

Abstract: A node in an optical communications network receives optical packets at its input. It determines a priority assigned to each optical packet. When the optical packet is a transit packet destined for another node then, if the packet is determined to have a relatively higher priority, it is output from the node via a continuous-flow transmission path. Other transmit packets having relatively lower priorities are sent via an alternative transmission path that may include queues or buffers resulting in a variable delay.

Abstract: At the transmitter end, route information is converted to allocated frequency mixes that are used to produce route signals by modulating a carrier signal. The route signals produced are placed in front of and/or after at least one data packet and are transmitted within an optical data packet stream. At the receiver end, the route information is evaluated in terms of the frequency mix used for the modulation and the data packets are switched using the route information obtained from the frequency mixes.

Abstract: An optical communications subsystem is proposed to permit the multiplexing of multiple, parallel electronic data streams onto a serial, very high speed optical data channel. The subsystem may also be used to generate programmable ultrafast optical data words for the testing of optical components, and system performance testing of very high speed data transmission systems. The key device component, based on a modified arrayed waveguide grating structure, is directly integratable with a high-speed optoelectronic modulator array in a simple, cost effect, and manufacturable configuration. Pulse spacings as small as 1 picosecond have been demonstrated corresponding to an effective data rate of up to one terahertz. An integrated optical pulse generator is configured to receive a laser light input and output an optical pulse train. Direct space-to-time pulse shaping and optical pulse train generation is achieved by use of an arrayed waveguide (AWG) that is double-passed.

Abstract: A first multimode interferometer has a first input port to which an optical signal is applied, a first output port, and a second output port. A first optical waveguide is connected to the first output port of the first multimode interferometer. The first optical waveguide has a refractive index changed in response to a trigger signal externally applied. A second optical waveguide is connected to the second output port. A triggering unit supplies, to the first optical waveguide, the trigger signal for changing the refractive index of the first optical waveguide. An optical switch is provided which can increase the processing speed, can reduce the device size, and is free from dependency on the polarization state of an optical signal.

Abstract: A system and method are disclosed for carrying additional information data on multiplexed signals which are modulated on different wavelengths. An information code such as an address or control data for a particular data signal at a selected wavelength is overlaid on the parallel multiplexed signals. The information code may be overlaid by attenuation or changing the amplitude of the different signals. A separate marker channel at a separate wavelength is also multiplexed with the data signals to indicate the presence of an information code. An optical data detector array is used to optically determine the encoded address by comparing the signals with light levels and producing an output when a matching code is detected. The optical data detector array uses a series of detectors each corresponding to the wavelength of light signals carrying the information data.

Abstract: A method and apparatus for generating a series of positive and negative signals from an optical signal. The optical signal is fed into a loop of optical fiber. The loop of optical fiber is provided with a first and second directional coupler. As the optical signal circulates through the optical loop, the first and second directional coupler extract a percentage of light from the optical signal, and couple the extracted light to a photodetector which converts the extracted light into electrical energy. The present invention also provides an impulse cancellation line. The impulse cancellation line is provided to neutralize the problematic initial light extracted from the optical signal in the first directional coupler and coupled to the photodetector. However, as the optical signal continues to circulate through the optical loop, the extracted light is not neutralized.

Abstract: Optical systems are provided. One such system includes an optical transmission path that is defined, at least partially, by a variable optical delay system. The variable optical delay system incorporates a variable refractive index component that is arranged to receive an optical signal. The variable optical delay system provides a control input to adjust a refractive index of the variable refractive index component so that latency of the optical signal can be altered. Methods and other systems also are provided.

Abstract: Methods and apparatus for multiplexing and demultiplexing optical signals. An interleaver having a modified Mach-Zehnder interferometer as a first stage is used as a wavelength division multiplexer. This first stage is combined with one or more cascaded stages, each having a beam splitter and an optical delay element. A light beam including a number of signals at different wavelengths is received. The beam is split such that approximately half of each signal is contained in one of two sub-beams. One of the two sub-beams passes through a delay element, which provides a phase shift. The two sub-beams are recombined and split again. Each wavelength adds constructively or destructively in the new sub-beams such that the signals are separated—some wavelengths are in one of the new sub-beams, some are in the other. One of these sub-beams is delayed, and the two are combined and split again, improving the separation.

Abstract: An optical network has an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit via a working optical fiber, (2) a protection OSU of a protection circuit via a protection optical fiber, and (3) one or more optical network terminals (ONTs). The present invention enables fast protection switching from the working OSU to the protection OSU. In one embodiment, the arrival times of corresponding upstream ranging reply PLOAM cells are measured at both the working and protection OSUs during ranging operations of the working OSU. In another embodiment, a cell delineation procedure is initiated at the protection OSU during normal, non-ranging operations of the working OSU to enable the protection OSU to correctly delineate upstream cells and the arrival times of corresponding upstream cells are then measured at both the working and protection OSUs.

Abstract: A dynamic gain flattening filter includes a first filter stage. The first filter stage has a first tunable coupling member and a first differential delay with first and second tunable delay paths. The first tunable coupling member adjusts an amount of power of the optical signal that is divided onto the first and second tunable delay paths of the first differential delay.

Abstract: Techniques and systems for monitoring of optical signals are described. Each of a plurality of optical signals is supplied to an optical port. A port signal is generated based on each of the optical signals and each of the port signals is subjected to a time delay to create a time delayed signal, with a different time delay being present in each of the time delayed signals. The time delayed signals are multiplexed to create a multiplexed signal comprising a plurality of multiplexed signal components, each component corresponding to one of the time delayed signals and exhibiting a time delay characterizing the corresponding time delayed signal. A desired one or ones of the multiplexed signal components are selected by analysis or display by specifying a time delay present in the time delayed signal represented by the desired component, and selecting a signal component exhibiting the specified time delay.

Abstract: A multi-wavelength light source apparatus includes a tunable light source, optical intensity modulator, optical coupler, annular optical delay circuit, and optical gate device. The tunable light source successively changes and outputs a plurality of output lights different in wavelength from one another. The optical intensity modulator outputs a modulated signal light obtained by modulating an amplitude of the output light outputted from the tunable light source over a predetermined time. The optical coupler is optically connected to the optical intensity modulator, and receives the light outputted from the optical intensity modulator. The annular optical delay circuit is optically connected to the optical coupler, and delays a part of the output light outputted from the optical intensity modulator over a time longer than the predetermined time.

Abstract: A system and method is disclosed for mitigating the scintillation and fading effects of baseband wireless, radio frequency wireless, optical wireless and satellite communication links. The system uses a space-time channel model to derive an optimal processing architecture for signal recovery through a scintillation channel. The signal power is collected by space-time sampling within the four dimensional volume of the spatial and temporal spread. Consequently, the space-time equalizer can effectively recover the lost signal power induced by the spreading effects of atmospheric scintillating medium. The advantages of this invention include a decrease in link outages resulting in higher link availability and more reliable data network services.

Abstract: A technique for switching all-optical packet switching is disclosed. In one embodiment, the technique is realized by receiving at least one data packet over a network, disassociating a payload portion from a first header in the data packet, forming a second header based on a first information in the first header, associating the payload portion with the second header to form a modified packet and switching the modified packet based on a second information contained in the first header.

Abstract: An optical device is provided comprising a delay region having a photonic band structure, an optical input, an optical output, wherein the optical input is adapted to couple input optical signals into a predetermined mode in the delay region such that the optical signal is slowed and wherein the optical output includes a wavelength selective element. Input optical signals are coupled into a highly dispersive mode in the delay region in which the group velocity of the optical signal is reduced. The input signal, which has been delayed and dispersed, is recovered at the output of the device using the wavelength selective element.

Abstract: A fully “time tunable” all-optical switch routes/switches digital bits (packets) in an all-optical format for transmission, or for further processing, in an all-optical communication network. The all-optical switch is implemented in either a semiconductor hybrid or in a completely monolithic form. Variable time delay elements adjust the time delay of a clocking signal input and a data packet input. The clocking signal determines the state of two nonlinear optical elements, such as semiconductor optical amplifiers, incorporated in the upper and lower arms of a Mach-Zehnder configuration. An optical coupler is connected to the output of the all-optical switch. The output of data from selected ports of the optical coupler is controlled using the variable time delay elements.

Abstract: A method and apparatus within an optical transmitter (300) for suppressing relative intensity noise (RIN) by generating at least two optical signals (305,310), each having differing wavelengths and combining the optical signals with a combiner (315) into a composite output signal, wherein the composite output signal has an output power value equal to the sum of the power value of the optical signals. The composite output signal is then transmitted over a communication medium, wherein information content of the optical signals are substantially equivalent, and wherein combining the optical signals before transmitting provides a reduction in RIN of the composite output signal compared to the RIN of a single optical signal transmitted over a communication medium.

Abstract: An optical TDM multiplexing apparatus to multiplex a plurality of input signals in the optical stage in the time domain according to the invention comprise a plurality of signal light sources to generate optical signals each having a wavelength different from the others to carry each of the plurality of the input signals, a timing adjuster to adjust timings between the respective optical signals so that each optical signal output from the plurality of the signal light sources is disposed on a time slot different from the others in the time domain, an optical multiplexer to multiplex each optical signal output from the timing adjuster in the wavelength domain and a wavelength converter to convert each wavelength of the output light from the optical multiplexer into a predetermined wavelength.

Abstract: An optical network has an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit, (2) a protection OSU of a protection circuit, and (3) one or more optical network terminals (ONTs), where an ONT has (i) a working line termination (LT) unit of the working circuit and connected to the optical splitter via a working optical fiber and (ii) a protection LT unit of the protection circuit and connected to the optical splitter via a protection optical fiber. The present invention enables fast protection switching from the working circuit to the protection circuit. The arrival times of corresponding downstream cells are measured at both the working and protection LT units of the ONT, and information related to the arrival times is transmitted from the ONT to the protection OSU.

Abstract: A programmable electro-optically controlled optical delay device providing multiple optical outputs. The optical delay device provides multiple output ports where the optical propagation delay increases at each port. An incident optical beam is propagated within electro-optically active material within the device, so that the propagation delay at each output port may be varied according to an applied voltage. In an optical beam steering system, the present invention provides true-time delay for multiple optical beams, allowing the beams radiated by the beam steering system to be time-coincident. The present invention provides for one or two dimensional beam steering.

Abstract: A light-controlled light modulator can achieve high-speed, low-loss wavelength conversion. Continuous light with a wavelength &lgr;j is launched into an MMI coupler via a port, and is split into two parts by the MMI coupler, which are led to a loop-type interferometer. In the loop-type interferometer, the two parts travel separately around the loop as clockwise traveling light and counterclockwise traveling light, are combined by the MMI coupler again via a filter-equipped phase modulator, thereby being emitted to the port. In this state, signal light &lgr;i(s) with a wavelength &lgr;i is launched into the filter-equipped phase modulator via a port. Even when the wavelength &lgr;i of the signal light &lgr;i(s) is equal to the wavelength &lgr;j of the wavelength converted output light, the wavelength conversion can be achieved with preventing noise from being mixed into the output light emitted from a port.

Abstract: In a signal demultiplexing device formed by a probe light source, a wavelength converter, and a wavelength demultiplexer, the probe light source is formed by a plurality of sub-probe light sources configured to respectively generate the sub-probe lights with the prescribed different wavelengths for respective time-slots, a multiplexer configured to multiplex the sub-probe lights generated by the plurality of sub-probe light sources, and a phase different giving unit configured to give phase differences corresponding to time-slot positions to the sub-probe lights multiplexed by the multiplexer, and to sequentially output the sub-probe lights with the phase differences in correspondence to respective time-slots.

Abstract: An optical system includes a delay region having a photonic band structure, a modulated optical signal source, an optical input, and an optical output. The optical input couples modulated input optical signals into a predetermined mode in the delay region such that group velocity of the optical signal is reduced. The optical output includes a wavelength selective element. Input optical signals are coupled into a highly dispersive mode in the delay region in which the group velocity of the optical signal is reduced. The input signal, which has been delayed and dispersed, is recovered at the output of the device using the wavelength selective element.

Abstract: It is an object of the present invention to provide an optical filter which allows parameters to be easily adjusted, which allows birefringence and temperature dependence to be easily compensated for, and which is essentially free from dispersion. The optical filter includes an optical coupler that splits light into two beams, optical couplers connected to outputs of the optical coupler, a first group of two optical waveguide delay lines connected to the coupler, a second group of two optical waveguide delay lines connected to the coupler, an optical coupler that combines lights from the first group of the lines, an optical coupler that combines lights from the second group of the lines, and a multimode interference optical coupler that combines lights from the couplers together.

Abstract: A switch is provided that receives user information through a plurality of framer circuits, which group the user information into frames. The frames are fed to a switch fabric including an array of switch elements, each having a switch matrix for routing each frame to a desired output in accordance with configuration data stored in a first table coupled to the switch matrix. If different outputs are desired, i.e., the switch matrix is to be reconfigured, a switch control circuit supplies additional switch configuration data to the frames through the inputs along with additional user information to be routed through the switch. While the additional switch configuration data is stored in a second table, data flow remains uninterrupted through the switch matrix.

Abstract: A communications network includes optical network terminations (ONTs) and an optical line termination (OLT) connected to a passive optical network (PON). The OLT measures round trip transmission delay expressed in time slot duration for each of the ONTs, and orders the ONTs in ascending order of respective delay modulo time slot duration. A desired reception time at the OLT is scheduled for each of the OLTs according to the ascending order and each ONT is commanded to transmit at a command time that leads the respective desired reception time by a respective delay integral time slot duration. The scheduling includes leaving a reception interval spare after the last ONT in ascending order. The ascending delay modulo slot protocol becomes more efficient as the number of time slots per frame increases. If the number of time slots per frame is N, then the efficiency of the protocol is (N−1)/N. Unassigned time required per transmission frame is thereby reduced.

Abstract: The present invention provides for a delay unit for optically generating time delays in signals comprising: a delay entrance plane, the delay entrance plane comprising at least one row of signal input positions, wherein each signal input position is adapted to receive an optical beam from a source; a delay exit plane, the delay exit plane comprising a respective number of rows of signal output positions, each signal output position is adapted to output the optical beam; and wherein each signal input position of a given row is connected by an optical fiber to a corresponding signal output position, each optical fiber of a given row being the same length as every other optical fiber of that row. Also provided are apparatus and methods for generating time delays in signals.

Abstract: Method and device are presented for controlling continuous propagation of input multi-frequency light through a tunable frequency selective optical filter so as to selectively direct a selected frequency band of the input light to a dropping/adding output channel of the device. Selective frequency coupling is applied to the input light to split it into first and second light components propagating through first and second spatially separating optical paths, respectively, such that the first light component comprises at least a portion of power of the selected frequency band of the input light, and the second light component comprises the remaining portion of the input light. A phase delay between the first and second optical paths is selectively created by adjusting the phase of the first light component.

Abstract: An optical transmission system capable of alleviating the non-linear optical effect from overhead portions of a bit pattern comprised of a plurality of bits, wherein a plurality of optical transmit devices input a clock signal of identical phase and frequency, and optical signals whose overhead positions are changed on each wavelength by respective variable delay lines under the control of a phase controller are sent to a transmit side WDM device. At the transmit side WDM device, these optical signals are multiplexed in a wavelength multiplexer and sent to the receive side WDM device. Receive side optical transmission devices receive the respectively isolated optical signals. A phase controller offsets the positions of the optical signals and sends them to the overhead on each wavelength so that the non-linear effect of the receive optical signal is suppressed and a satisfactory signal can be received.

Abstract: A system and method are disclosed for carrying additional information data on multiplexed signals which are modulated on different wavelengths. An information code such as an address or control data for a particular data signal at a selected wavelength is overlaid on the parallel multiplexed signals. The information code may be overlaid by attenuation or changing the amplitude of the different signals. A separate marker channel at a separate wavelength is also multiplexed with the data signals to indicate the presence of an information code. An optical data detector array is used to optically determine the encoded address by comparing the signals with light levels and producing an output when a matching code is detected. The optical data detector array uses a series of detectors each corresponding to the wavelength of light signals carrying the information data.

Abstract: An x-ray inspection system for automatically detecting nuclear weapons materials generates a high energy x-ray fan beam or a traveling x-ray pencil beam that traverses an object under inspection. An x-ray detector detects x-ray energy that passes through the object and provides a detected signal indicative thereof. The detected signal is processed to detect the presence of an area of very high x-ray attenuation within the object under inspection, which is indicative of nuclear weapons materials. Because of the high atomic number (Z) and high density of nuclear weapons materials Uranium and Plutonium, both of these materials attenuate (i.e., absorb) incident x-rays significantly more than ordinary materials. That is, very high Z materials such as nuclear weapons materials, produce no x-rays outside of their block of material because the x-rays are self absorbed within the very high Z materials.