Abstract: An optoelectronic timing system includes an adaptive frequency generator system in which optical pulses are developed by a semiconductor laser. The pulses are directed into a number of time-quantifiable optical paths. Time quantification for a pulse is based upon the time required for a pulse to travel a particular length at the speed of light. Pulses are recombined at a nodal point and exhibit a numerical relationship with the periodicity of the issued pulse train equal to the numerical relationship between the lengths of the number of optical waveguides. A pulse detector and a regenerator are coupled to the semiconductor laser. A regeneration waveguide having a length equal to the longest of the optical paths is coupled to receive pulses from the laser.

Abstract: A method of establishing a system delay time and a frame length in a Time Division Duplexing (TDD) system includes adjusting time lengths of an uplink (UL) frame, a downlink (DL) frame, a Transmit/receive Transition Gap (TTG), and a Receive/transmit Transition Gap (RTG); a Base Station (BS) transmitting a DL frame and receiving a UL frame; and a Mobile Station (MS) receiving the DL frame and transmitting the UL frame.

Abstract: Disclosed are a method and a system for generating switching control signal separating transmission signal on an access point and a mobile communication terminal in an optical repeater employing, for example, a TDD scheme. The method includes the steps of generating a control signal for generating a switching control signal in transmitting data from the AP and transmitting the control information to a remote during an idle time interval, detecting synchronization information on the downlink signal and time-delay information from the control information, delaying a time interval between the synchronization information and a starting point of the downlink signal, generating the switching control signal for the downlink signal according to the transmission time information of the downlink signal, and performing a switching operation according to the switching control signal and setting a downlink path.

Abstract: An OTDM-DPSK signal generator includes an optical splitter, a first and a second phase modulator, an optical coupler, and a monitor signal splitter. The optical splitter splits an optical pulse string into a first and a second optical pulse string. The first and second phase modulators generate a first and a second channel DPSK signal, respectively. The DPSK signals are provided with one bit delay to generate another DPSK signal, which enters the optical coupler, which outputs an OTDM-DPSK signal, which enters a monitor signal splitter. The monitor signal splitter splits from the OTDM-DPSK signal a monitor signal and inputs the monitor signal to an optical carrier phase difference detector. The detector generates an optical carrier phase difference detection signal as a function of an optical carrier phase difference between optical pulses. The optical carrier phase difference can thus be detected between optical pulses in an OTDM-DPSK signal.

Abstract: A system and method are provided for calibrating temporal skew in a multichannel optical transport network (OTN) transmission device. The method accepts a pair of 2n-phase shift keying (2n-PSK) modulated signals, as well as a pair of 2p-PSK modulated signals. The 2n-PSK and 2p-PSK signals are converted to 2n-PSK and 2p-PSK optical signals, respectively. The 2n-PSK and 2p-PSK optical signals are orthogonally polarized and transmitted. A timing voltage is generated that is responsive to the intensity of the orthogonally polarized signals. The timing voltage is correlated to a reference frame calibration pattern associated with a preamble/header portion of an OTN frame. Then, the timing voltages associated with the Ix, Qx, Iy, and Qy signal paths are compared, and the misalignment between the timing voltages and the reference frame calibration pattern is minimized in response to adjusting time delay modules in the Ix, Qx, Iy, and Qy signal paths.

Abstract: A system and method are provided for controlling time delay in a multichannel optical transport network (OTN) transmission device using time domain reflectometry (TDR) measurements. The method accepts a pair of 2n-phase shift keying (2n-PSK) modulated signals via Ix and Qx electrical signal paths, where n>1. Likewise, a pair of 2p-PSK modulated signals are accepted via Iy and Qy electrical signal paths where p>1. Using TDR modules, signal reflections are measured from an output port for each signal path. The method minimizes time delay differences in the signal reflections for the Ix, Qx, Iy, and Qy signals paths by using the signal reflection measurements to adjust time delay modules in each signal path.

Abstract: A method for programming the delay for a node in a communication system is disclosed. The node receives a selected delay value and a signal path delay value indicating a delay for signals communicated to the node. The signal path delay comprises an aggregation of transport delays calculated by each node for segments of the communication system between the node and a host node. The method further calculates an additional delay necessary to meet the selected delay value.

Abstract: One embodiment of the invention provides an optical signal synchronizer having a plurality of optical channel synchronizers. Each optical channel synchronizer receives a respective input wavelength division multiplexing (WDM) signal and processes it to produce a corresponding output WDM signal, in which optical data packets corresponding to different carrier wavelengths are synchronized to each other regardless of the presence or absence of such synchronization in the input WDM signal. The optical signal synchronizer further has an optical multiplex synchronizer that receives the output WDM signals from the optical channel synchronizers and synchronizes them to each other and to an external reference clock without demultiplexing any of them into individual WDM components.

Abstract: Regarding the passive optical network (PON) system of the present invention, in an OLT, data of different bit rates is framed, and framed data rows are subjected to FEC encoding processing without changing the line up of the data, and a check bit is added to the end of the frame, and an optical signal that has been modulated in accordance with the data row to which the check bit has been added is transmitted to the optical transmission line. Then in an ONU that corresponds to a high speed bit rate to which an optical signal from the OLT has been applied via a power splitter, forward error correction of the reception data is performed. As a result in a PON system in which data of different bit rates coexist, the minimum reception rate of a high speed ONU can be improved without having an influence on a low speed ONU.

Abstract: In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal to create a delayed electrical signal that compensates for a DGD of the optical line, and combining the delayed electrical signal with the first electrical signal to produce a fixed output electrical signal.

Abstract: An electronic device [200] includes a housing [100] for containing circuitry [205] that generates a light beam. The electronic device includes pivotal portions [105, 110] of the housing. A light receiver [245] is associated with one of the housing pivotal portions. A light redirecting mechanism [215] is mounted at a predetermined location of the housing other than to the one pivotal portion thereof and is configured to redirect the light beam in a plurality of predetermined optical paths in which the light receiver is disposed with relative pivoting between the housing pivotal portions.

Abstract: The invention relates to a device and a method for converting WDM signals into an OTDM signal. The device comprises shifting means (102, 103, 104) adapted to introduce a time shift between the pulses of the WDM signals carried by the optical carriers, modulation means (112, 113, 114) adapted to modify the optical power of the WDM signals, an optical temporal multiplexer/demultiplexer (120), a birefringent propagation medium (130) into which the WDM signals are injected in such a manner as to achieve a soliton trapping phenomenon, and absorption means (140) adapted to introduce optical losses into the components of the OTDM signal. This device performs WDM/OTDM conversion at very high bit rates. It also performs OTDM/WDM conversion. It is intended to be installed in long-haul telecommunication networks.

Abstract: An optical phase difference control system is provided for controlling a phase difference of a single optical time-division multiplexed signal obtained by multiplexing a plurality of modulated optical signals encoded. The control system includes an interferometer and a low-frequency extractor. The interferometer is used for receiving part of the optical time-division multiplexed signal to split it into first and second signals, giving, between the first and second signals, a phase difference equivalent to one bit of the optical time-division multiplexed signal, and thereafter multiplexing the first and second signals. The low-frequency extractor is used for adding together signals, output from the interferometer, which have the similar intensity every two successive bits, and extracting a low-frequency waveform signal as a signal for controlling the phase difference of the single optical time-division multiplexed signal.

Abstract: A method for registration of multiple entities belonging to a specific optical networks unit (ONU). In one embodiment, the multiple entity registration method comprises checking by an optical line terminal (OLT) if a registration request message (400) received from the specific ONU belongs to a certain grant (402), and based on the check result, registering an entity as either a first (408) or as an additional entity (404) of the specific ONU. In another embodiment, the method comprises checking by an OLT of a reserved value of a flags field (502) inside a registration request message (500), and based on the check result, registering an entity as either a first (508) or as an additional entity (504) of the specific ONU. The knowledge by an OLT that multiple entities belong to a specific ONU is used for grant optimization and packet data flow optimization.

Abstract: An optical time delay module has a plurality of time delay elements connected in a series and a plurality an optical output couplers wherein each of said optical output couplers is operationally connected between one or more time delay elements in said series, the optical output couplers providing a plurality of optical outputs from said module with different optical delays controlled by an analog voltage.

Abstract: An optical time delay module has a plurality of time delay elements connected in a series and a plurality an optical output couplers wherein each of said optical output couplers is operationally connected between one or more time delay elements in said series, the optical output couplers providing a plurality of optical outputs from said module with different optical delays controlled by a digital control word.

Abstract: The present invention is an optical multiplex communication system in which an optical wavelength division channel and an optical code division channel can coexist, wherein a WDM channel section 86 has a wavelength demultiplexer 36 and WDM channels W1 to W4. An optical pulse string 83-3 is demultiplexed by the wavelength demultiplexer 36, and for channel W1, an optical pulse 37 with wavelength ?1 is input to an intensity modulator 114 and converted into an optical pulse signal of channel W1, and is output as a wavelength division optical pulse signal 115, where transmission information of channel W1 is reflected.

Abstract: A method for registration of multiple entities belonging to a specific optical networks unit (ONU). In one embodiment, the multiple entity registration method comprises checking by an optical line terminal (OLT) if a registration request message received from the specific ONU belongs to a certain grant, and based on the check result, registering an entity as either a first or as an additional entity of the specific ONU. In another embodiment, the method comprises checking by an OLT of a reserved value of a flags field inside a registration request message, and based on the check result, registering an entity as either a first or as an additional entity of the specific ONU. The knowledge by an OLT that multiple entities belong to a specific ONU is used for grant optimization and packet data flow optimization.

Abstract: The polarization multiplexed light transmitter takes out a part of a polarization multiplexed light to be transmitted as a monitor light; makes orthogonal polarization components contained in the monitor light to interfere with each other, to generate a polarization interfering light; converts the polarization interfering light into an electric signal; measures the power of an alternate current component contained in the electric signal after eliminating a direct current component thereof; and feedback controls delay amount varying sections so that an inter-polarized channel delay time judged based on a change in the measured power reaches a predetermined value. Thus, the delay time between the orthogonal polarization components in the polarization multiplexed light can be varied flexibly at a high speed with a simple configuration, and thus, it becomes possible to suppress transmission characteristics degradation of the polarization multiplexed light due to a change in system state.

Abstract: A system and method are provided for controlling time delay in a multichannel optical transport network (OTN) transmission device using time domain reflectometry (TDR) measurements. The method accepts a pair of 2n-phase shift keying (2n-PSK) modulated signals via Ix and Qx electrical signal paths, where n>1. Likewise, a pair of 2p-PSK modulated signals are accepted via Iy and Qy electrical signal paths where p>1. Using TDR modules, signal reflections are measured from an output port for each signal path. The method minimizes time delay differences in the signal reflections for the Ix, Qx, Iy, and Qy signals paths by using the signal reflection measurements to adjust time delay modules in each signal path.

Abstract: Each of a plurality of semiconductor optical amplifiers operates as an optical gate switch and selects an optical signal indicated by a gate control signal from an optical gate switch control unit. A plurality of photodetectors monitor the power of an optical signal input through a corresponding input port. A VOA control unit calculates an amount of attenuation corresponding to each input port based on the power of each optical signal. A variable optical attenuator attenuates the selected optical signal according to the calculated amount of attenuation in synchronization with the gate control signal.

Abstract: A demodulator comprises an input splitter, optical device sets, and couplers. The input splitter splits an input signal comprising symbols to yield a number of signals. A first optical device set directs a signal of along a first path. A second optical device set directs another signal along a second path to yield a delayed signal. At least a portion of the second path is in free space. A path length difference between the first path and the second path introduces a symbol delay between the first signal and the second signal. A coupler receives a portion of the signal and a portion of the delayed signal to generate interference, where the interference indicates a phase shift between a phase corresponding to a symbol and a successive phase corresponding to a successive symbol.

Abstract: An optical modulating circuit realizing a PPM is constituted by circuit parts having a frequency band equal to a data rate to provide a technique which increase the data rate. A first light source generates a first single wavelength signal serving as a continuous light having a first wavelength ?1 as a wavelength of a carrier wave. A second light source generates a second single wavelength signal serving as a continuous light having a second wavelength ?2 different from ?1 as a wavelength of a carrier wave. For the first single wavelength signal and the second single wavelength signal, according to a transmission electric signal having information 0 or 1, an optical switch outputs a first single wavelength signal as an input optical signal when the information is 0. On the other hand, when the information is 1, the optical switch outputs the second single wavelength signal as an input optical signal.

Abstract: A method of providing a multi-wavelength light source includes the steps of modulating an optical pulse source so as to output optical pulses with a designated repetition frequency, time-division multiplexing the optical pulses output by the optical pulse source so as to output optical pulses with a repetition frequency which is an integral multiple of the designated repetition frequency, and demultiplexing wavelengths of the optical pulses with the repetition frequency which is the integral multiple of the designated repetition frequency so as to output the wavelengths as the multi-wavelength light source.

Abstract: A method and apparatus for implementing an RF photonic transversal filter that utilizes tap apodization and wavelength reuse to obtain a high side lobe suppression together with narrow and configurable passbands. Several taps are obtained from one wavelength by using dispersive optical delay lines such as chirped fiber gratings that introduce a delay between successive wavelengths. A selected subset of the input wavelengths is utilized to generate multiple taps per wavelength. Some of the taps are apodized to generate various filter transfer functions that yield a high side lobe suppression ratio.

Abstract: An optical signal multiplexing device includes a delay-amount adjusting unit that converts wavelengths of optical signals to be multiplexed when the optical signals are obtained, and adjusts delay amounts of the optical signals by passing the wavelength-converted optical signals through waveguides that generate propagation delays corresponding to the wavelengths in the optical signals. The optical signal multiplexing device also includes a waveform-degradation compensation unit that compensates for degradation of a waveform of the optical signals while keeping a difference of propagation delay times between the optical signals delay amounts of which are adjusted by the delay-amount adjusting unit.

Abstract: A channel switching function is added to a wavelength division multiplexing passive optical network (WDM-PON) system, which is an access optical network system, and the potential transmission rate is increased by combining wide wavelength tunable lasers and a time division multiplexing (TDM) data structure and properly using the necessary optical components. In addition, when the wavelength of a light source or an arrayed waveguide grating (AWG) changes, the wavelength is traced and the magnitude of a transmitted signal is maximized without an additional detour line using a loop-back network structure. Furthermore, fewer thermo-electric controllers (TECs) are required for stabilizing the temperature of an optical line terminal (OLT) using wavelength tunable lasers, each laser electrically changing its wavelength.

Abstract: A RF-synchronization system includes a laser that creates pulse trains for synchronization. A modulation means transfers the timing information of the pulse train into an amplitude modulation of an optical or electronic system. A synchronization module changes the driving frequency of the modulation means until it reaches a phase-locked state with the pulse train.

Abstract: The present invention inputs a signal synthesized an optical pulse with a variable-wavelength laser beam different in wavelength from it to a delay unit (S1). The delay unit branches the signal to two optical signals, produces an optical path difference between them to afford a delay, synthesizes them again to generate a multiplexed optical signal, and minutely varies the optical path length of one of them (S2) The present invention measures output variance of the delay unit on a variable-wavelength laser beam resulting from the minute variance (S3), and controls the optical path difference so as to minimize output variance at a position where the output is a maximum or minimum, or is a specific value other than them (S4). This stabilizes a phase difference between adjacent pulses of the multiplexed optical signal outputted from the delay unit (5) with a simple construction in optical time division multiplexing technology.

Abstract: Amplitude modulation is performed for a signal light with a modulation signal having the same cycle as that of an optical pulse to be extracted by using an optical modulator. At this time, timing is adjusted so that the peak of the optical pulse of the channel to be extracted of the signal light becomes the largest. A spectrum of the amplitude-modulated signal light is expanded according to the size of the peak of the optical pulse by a spectrum expander. Then, part of the expanded spectrum is extracted with a band pass filter, whereby the optical pulse of the desired channel is extracted.

Abstract: An optical buffer device includes plural optical memory elements that are capable of holding light and an optical delay element. The plural optical memory elements are arranged on an optical path through which signal light and control light propagate in mutually opposite directions. Further, the optical delay element is disposed between the optical memory elements that are adjacent to each other. The optical delay element imparts different delays to the signal light and the control light. According to a preferred exemplary embodiment of this optical buffer device, each of the optical memory elements includes an optical waveguide through which the signal light and the control light propagate and an optical resonator that is disposed in proximity to this optical waveguide, and a coupling between the optical waveguide and the optical resonator is generated or cancelled depending on whether or not the control light is inputted.

Abstract: A device and a method for converting WDM signals into an OTDM signal. A time shift is introduced between the pulses of the WDM signals carried by the optical carriers. A modulation means is (112, 113, 114) adapted to modify the optical power of the WDM signals, and an optical temporal multiplexer/ demultiplexer (120) is provided. The WDM signals are injected into a birefringent propagation medium (130) in such a manner as to achieve a soliton trapping phenomenon. An absorption means (140) is adapted to introduce optical losses into the components of the OTDM signal. This technique performs WDM/OTDM conversion at very high bit rates. It also performs OTDM/WDM conversion. It is intended to be installed in long-haul telecommunication networks.

Abstract: A network element for incorporating in nodes of a network that is a transparent, subwavelength networks. The element is configurable and adapted to support an arbitrary protocol, with protocol-specific monitoring features as well as protocol-independent add/drop capability. An arrangement that allows transmission of client signals with higher clock fidelity is achieved by developing a phases offset measure at an ingress node, communicating it to the egress node, and recovering the client's clock from the received data and from the received phase-offset information. The ability to recover the client's clock with high fidelity is enhanced by modified pointer processing in intermediate nodes of the network that the client's signal traverses. The pointer processing is modified to inject positive and negative justifications in excess of what is minimally necessary to insure proper transmission over a network that employs a protocol involving framing layer frames embedded in communication layer frames.

Abstract: All-optical system for generating high rate modulated signals. The system includes: a signal generator for generating a first periodic signal at a first rate; an optical chopping device arranged to receive the first periodic signal and to produce therefrom a second periodic signal having pulses that are narrower than the pulses of the first periodic signal; a splitting device for receiving and splitting the second periodic signal into multiple images of the second periodic signal to propagate along multiple optical paths, the multiple optical paths including optical modulators for modulating the images of the second periodic signal to produce modulated signals; and an interleaving device for receiving and interleaving the modulated signals to produce a stream of modulated signal having a second rate which is higher than the first rate.

Abstract: A communication system for the mutual interconnection of a plurality of lower traffic level (5 Terabit) switch nodes via a relatively higher traffic level (Petabit) connection bus, which system comprises in operative association with each node, a two part TDM optical data management interface, wherein a first of the two parts comprises a time slot resequencer which serves to provide for the transmission of data from its associated node to the bus, and wherein a second of the two parts comprises a time slot specific combiner which serves for the transmission of data from the bus to its associated node, each node and the bus having independent data scheduling.

Abstract: Optical transmission equipment, capable of electrically adjusting the delay difference between a plurality of digital signal paths to be connected to a multilevel optical modulation unit or demodulation unit, having multiplexing circuits connected to the digital signal paths and a delay adjustment unit inserted in one of the digital signal paths to adjust delay of N-bit-parallel low-speed digital signals with the timing unit of a bit period of a high-speed serial digital signal to be outputted from multiplexing circuit.

Abstract: A time-multiplexed waveform generator includes a wavelength splitter that receives an input optical signal and spectrally separates the input optical signal into a plurality of frequency components. A plurality of intensity modulators receives each of the frequency components and passes each of the frequency components for a selective time period, and then extinguishes that frequency for the remainder of a chirp time, the plurality of intensity modulators producing a plurality of first output signals. A plurality of adjustable delay lines is positioned after the intensity modulators and receives the first output signals. Each of the adjustable delay lines enables phase control of each of the frequency components associated with the first output signals for compensating any relative drifts of the path lengths and phase coherently stitching a plurality of sub-chirps together. The adjustable delay lines produce a plurality of second output signals.

Abstract: In an optical packet processing apparatus, an optical coupler joins optical packets transmitted through a plurality of input side optical transmission lines and outputs the joined optical packets to an output side optical transmission line. The optical packet processing apparatus has delay sections for delaying desired optical packets for each input side optical transmission lines. Delay times of the delay sections are different by one optical packet time period, while a minimum delay time thereof is the optical packet time period or more.

Abstract: In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal to create a delayed electrical signal that compensates for a DGD of the optical line, and combining the delayed electrical signal with the first electrical signal to produce a fixed output electrical signal.

Abstract: A method for programming the delay for a node in a communication system is disclosed. The node receives a selected delay value and a signal path delay value indicating a delay for signals communicated to the node. The signal path delay comprises an aggregation of transport delays calculated by each node for segments of the communication system between the node and a host node. The method further calculates an additional delay necessary to meet the selected delay value.

Abstract: A laser provides a cavity with complementary wavelength-dependent delay elements to provide the same optical length but time-staggered light paths for different colors. This provides the ability to individually control multiple narrow bands of colors each in a separate time division window.

Abstract: A receiver for an OTDM/PDM pulse train (10) in which the pulses (12) have alternating polarizations (P1, P2) has a polarization insensitive optical switch (16; 161, 162, 163, 164) for isolating optical pulses (10?) within the pulse train (10), and a polarization selective element (17) for separating from the isolated pulses (10?) at least one component that has a single polarization. This allows to considerable relax the constraints posed on the switch since components in the isolated pulses that result from interchannel interference can, at least to a large extent, be eliminated by the subsequent polarization selective element (17).

Abstract: An optical receiving apparatus sets, efficiently and optimally, a delay interferometer and a variable wavelength dispersion compensator in the apparatus.

Abstract: A group delay compensation equalizer is disclosed that employs a single channel four-port WDM device for compensating the group delay experienced by a plurality of wavelengths transmitted over different paths. The transmission differential between two wavelengths is compensated by transmitting the two wavelengths through two different paths where the fiber length in reflecting the second wavelength is equal to the transmission time difference between the two wavelengths. The single channel four-port group delay equalizer effectively provides a unidirectional signal flow, as compared to the conventional equalizer that transmits optical signals bi-directionally. The present invention reduces the cost of a group delay equalizer by simplifying the use of multiple three-port WDM devices into a single channel four-port WDM device.

Abstract: An upstream signal timing control method which controls a timing of an upstream optical signal, from a terminal device to a center device, to a timing that the center device intends. Optical clock pulses synchronized with the timing that the center device intends are sent from the center device to the terminal device. The terminal device delay-controls the optical clock pulses and retransmits them to the center device. The center device detects an offset between the timing and a timing of the returned optical clock pulses, and applies timing offset information to the transmitted optical clock pulses. The terminal device performs the delay control in accordance with the timing offset information applied to the received optical clock pulses. When the offset between the timing and the returned optical clock pulse timing is at or below a threshold, the center device verifies completion of timing control of the upstream optical signal.

Abstract: An optically sampling device optically samples an optical analog signal using a sampled signal having a predetermined sampling frequency, and outputs control light having a pulse train of an optically sampled optical analog signal. A signal generating device generates a pulse train of signal light which is synchronized with the sampled signal. An optical encoding device optically encodes the pulse train of the signal light according to the control light, by using optical encoders each including nonlinear optical loop mirrors, and outputs pulse trains of optically encoded signal light from said optical encoders, respectively. An optically quantizing device performs optical threshold processing on the pulse trains of optically-encoded signal light to optically quantize them, by using at least one of optical threshold processors each of which is connected to each of said optical encoders and includes a nonlinear optical device, and outputs optically quantized pulse trains as optical digital signals.

Abstract: An optical signal multiplexing device includes a delay-amount adjusting unit that converts wavelengths of optical signals to be multiplexed when the optical signals are obtained, and adjusts delay amounts of the optical signals by passing the wavelength-converted optical signals through waveguides that generate propagation delays corresponding to the wavelengths in the optical signals. The optical signal multiplexing device also includes a waveform-degradation compensation unit that compensates for degradation of a waveform of the optical signals while keeping a difference of propagation delay times between the optical signals delay amounts of which are adjusted by the delay-amount adjusting unit.

Abstract: Method and apparatus for compensating for first-order Polarization Mode Dispersion in an optical transmission system. An apparatus has a polarization controller for transforming polarization components of an optical signal carried by the optical fiber into orthogonal polarization states, a variable delay line for introducing a variable differential time delay between the polarization states and for producing an output optical signal that is compensated for PMD in the optical fiber, and a feedback unit for adjusting the polarization controller and the variable delay line to compensate for variations in the PMD of the optical fiber, the feedback unit including apparatus for generating a plurality of independent control signals to independently control actuators of the polarization controller and the variable delay line. The invention provides for a reduction in response time of the actuators and a reduction in complexity of an algorithm used to control the apparatus.

Abstract: A LADAR apparatus and a method for use in receiving a LADAR signal are disclosed. The apparatus includes an optical pickup capable of picking up a plurality of optical signals; a timing synchronization reference; a time domain multiplexer capable of multiplexing the optical signals into a multiplexed optical signal relative to the timing synchronization reference; and an optical detector capable of detecting the multiplexed optical signal. The method include time domain multiplexing a plurality of LADAR signals into multiplexed LADAR signal; detecting the multiplexed LADAR signal; and demultiplexing the detected LADAR signal.

Abstract: A method and apparatus for stretching a pulse, shaping a stretched pulse, and modeling a stretched and/or shaped pulse are disclosed. An etalon has a port, a partially reflective surface, and a fully reflective surface. A base pulse is introduced into the etalon, and a plurality of portions of the base pulse propagating from the etalon are collected. The collected portions are then combined to generate a stretched pulse whose width is proportional to the width of the base pulse. This can be modeled by assigning a transmission factor value to each one of a plurality of tags and a reflection factor value to each one of the taps, excepting only one tap. A transport delay for is assigned to each tap to which a reflection factor value was assigned, wherein the transport delay is proportional to the width of a base pulse.