Abstract: The disclosed systems, structures, and methods are directed to an optical transceiver, employing a first optical time domain reflectometer (OTDR) module configured to generate a first OTDR signal, and a second OTDR signal, the second OTDR signal being a delayed version of the first OTDR signal, a first optical supervisory channel (OSC) transmitter configured to generate a first OSC signal, and a second OSC signal, the second OSC signal being a delayed version of the first OSC signal, a first wavelength division multiplexer (WDM) configured to transmit the first OSC signal interleaved with the first OTDR signal on a first optical fiber and a second WDM configured to transmit the second OSC signal interleaved with the second OTDR signal on a second optical fiber.

Abstract: Techniques for imaging are disclosed. In one example, the disclosure is directed to a sensor positioned on an elongate optical fiber. The sensor comprises a plurality of blazed Bragg gratings configured to generate acoustic energy for imaging a region in response to a first optical signal, an interferometer configured to sense acoustic energy from the region and to provide a responsive second optical signal, the interferometer including a first fiber Bragg grating (FBG) and a second FBG, wherein the plurality of blazed Bragg gratings are positioned between the first and second FBGs.

Abstract: A light detection and ranging system is provided that includes first and second optical beams that are nondegenerate and are chirped antiphase. Taps split the first and second optical beams into first and second high-power and low-power path optical beams. An optical frequency multiplexer combines the first and second high-power path optical beams into a single spatial mode optical beam, which lensing optics launches towards a target, and collects light incident upon the target into a return path. An optical frequency demultiplexer splits the return optical beam into first and second spatial mode optical beams, and mixers mix the first spatial mode optical beam and the first low-power path optical beam, and the second spatial mode optical beam and the second low-power path optical beam, to produce optical beams having first and second beat frequencies, which optical detectors detect and from which range and velocity of the target are determinable.

Abstract: A media converter has an electrical bus port for connecting a first electrical bus; and an optical bus port for connecting an optical bus. The media converter is configured to convert an electrical signal of the first electrical bus into an optical signal of the optical bus in such a way that, at a first value of an internal control signal of the media converter, the optical signal corresponds to the electrical signal and, at a second value of the internal control signal, the optical signal has an inverted shape corresponding to the electrical signal. In a transmission phase during which the internal control signal changes from the first value to the second value, the media converter is configured to emit the optical signal in such a way that the optical signal corresponds to the electrical signal until the end of the transmission phase.

Abstract: A light detection and ranging (LiDAR) core is provided that transmits optical beams, and detects return optical beams. The transmitted optical beams are antiphase chirps that sweep a frequency band, and the sweep of the antiphase chirps includes multiple sub-sweeps over respective sub-bands of the frequency band. The system routes the transmitted optical beams that are launched towards a target, and receives light incident upon the target into the return optical beams. The system simultaneously measures and thereby produces multiple simultaneous measurements of first and second beat frequencies per sweep of the antiphase chirps, from the transmitted and returned optical beams, and includes a simultaneous measurement of the first and second beat frequencies per sub-sweep of the multiple sub-sweeps. And the system determines a range and velocity of the target from the multiple simultaneous measurements of the first and second beat frequencies per sweep of the antiphase chirps.

Abstract: An optical line terminal or an optical network unit first obtains link communication quality of both a first physical link and a second physical link between the optical line terminal and the optical network unit, performs FEC encoding on the first physical link by using a first FEC code, and performs FEC encoding on the second physical link by using a second FEC code. The link communication quality of the first physical link is higher than that of the second physical link, and encoding performance of the second FEC code is higher than that of the first FEC code. Based on the foregoing technical solutions, a FEC encoding type may be selected flexibly based on communication quality of different physical links. FEC encoding having relatively low FEC encoding performance is used for a link in a good state, to reduce overheads, bandwidth, and energy consumption.

Abstract: An optical module includes a substrate with a plurality of pairs, which are parallel to each other, spaced in a width direction of the substrate, of optical waveguides formed thereon, each pair being made up of a first optical waveguide that guides a first beam and a second optical waveguide that guides a second beam that monitors the first beam, and a lens that has an incident surface facing at least one pair of the plurality of pairs, collimates, for each of the at least one pair, the first and second beams that emerge from the pair and that differ from each other in at least any one of their incident positions and incident directions on the incident surface, and directs the first and second beams having been collimated and leaving the lens in different directions that depend on the incident positions or the incident directions.

Abstract: An optical transceiver comprising an optical signal input, a first modulation section coupled to the optical signal input, a second modulation section coupled to the optical signal input and positioned in serial with the first modulation section, wherein the first modulation section comprises a first digital electrical signal input, a first digital driver coupled to the first digital electrical signal input, and a first modulator coupled to the first digital driver, and wherein the second modulation section comprises a second digital electrical signal input, a second digital driver coupled to the second digital electrical signal input, and a second modulator coupled to the second digital driver, and an optical signal output coupled to the first modulation section and the second modulation section.

Abstract: Techniques for imaging are disclosed. In one example, the disclosure is directed to a sensor positioned on an elongate optical fiber. The sensor comprises a plurality of blazed Bragg gratings configured to generate acoustic energy for imaging a region in response to a first optical signal, an interferometer configured to sense acoustic energy from the region and to provide a responsive second optical signal, the interferometer including a first fiber Bragg grating (FBG) and a second FBG, wherein the plurality of blazed Bragg gratings are positioned between the first and second FBGs.

Abstract: A method for making IEEE 1588 master clock configuration for an ONU in a PON includes creating a PTP port on a UNI of the ONU, and generating a corresponding PTP port ME for the PTP port to indicate that the UNI is operating in a master clock mode; generating a 1588 master clock configuration data ME based on PTP port MEs of all PTP ports in the ONU, to store profiles of all PTP ports used as master clock devices; and generating a clock data set ME according to the 1588 master clock configure data ME, to indicate clock source information of all PTP ports used as master clock devices.

Abstract: A method for measuring a distributed physical value of an optical device under test (DUT), includes the steps of: launching into the DUT a probe signal that includes a plurality of optical pulses at at least one test wavelength, and receiving at least one optical signal backscattered by the DUT, wherein the optical pulses are obtained with at least the following steps: generating a first time sequence of first pulses that corresponds to a word of a first code, the first time sequence lasting not shorter than a time of flight and being formed by a number of time slots that is equal to the number of bits of the word of the first code; generating a second time sequence of second pulses that corresponds to a word of a second code; and amplitude modulating the second time sequence with the first time sequence.

Abstract: An optical module has an optical modulator configured to perform phase modulation on each of divided light components of an input light and output at least two phase-modulated signal lights, a semiconductor optical amplifier configured to amplify the phased-modulated signal lights in a same polarization mode, and a polarization multiplexer configured to convert the amplified signal lights into two orthogonally polarized signal lights and multiplex the orthogonally polarized signal lights.

Abstract: This invention relates to methods and devices for clock synchronization. The invention has particular application in the alignment of slave clocks to a master clock and in dealing with transmission delay asymmetries where the forward and reverse communication paths between the master and slave clocks have asymmetric transmission rates. Such methods and devices have particular application in small cell backhaul solutions for 4G/LTE deployments. In embodiments of the invention, the slave clock uses link rate information to estimate the transmission delay asymmetry and thus estimate the offset and skew of the slave clock. Embodiments provide a simple linear approximation technique and a Kalman filter-based technique for estimating offset and skew of the slave clock.

Abstract: Methods and apparatus for use in coherent transmission and reception of optical data signals. An integrated optics block (100) for use in a coherent optical transmitter comprising: a beam splitter (102) configured to split an input light signal into first and second input light signals, to output the first input light signal for use in an optical transmitter chip and to output the second input light signal for use as a local oscillator signal; a polarization combiner (104) configured to combine first and second received modulated light signals to form an output; and a polarization rotator (106) configured to rotate the polarization of the second modulated light signal such that it is substantially orthogonal to the polarization of the first modulated light signal prior to combining.

Abstract: An aspect of the present invention is an optical modulator, comprising a waveguide substrate and a multiplexing optical system. The waveguide substrate includes a first modulation portion, a second modulation, a first optical path and a second optical path. The multiplexing optical system includes a first surface and a second surface. First output light output from the first optical path and second output light output from the second optical path are input from the first surface and are output after there are combined at a combining point of the second surface. An optical path length between the first surface and the combining point in the first output light is larger than that of in the second output light. An optical path length between the first modulation portion and the first surface and an optical path length between the second modulation portion and the first surface are different.

Abstract: Systems and methods for accurately calculating the latency of a data-network, by providing an electronic device that receives data packets moving across a network data point and compares their time of arrival with a timestamp stored within a data packet. The electronic device may calculate the average latency by comparing N number of data packets. Further systems and methods for comparing the latencies at N number of electronic devices placed at unique network data points and calculating latencies between each device.

Abstract: An optical transmission device includes an error correction scheme determining unit, an error correction encoder, a modulation format determining unit and an optical transmitter. The error correction scheme determining unit determines an error correction scheme based on a latency between the optical transmission device and a correspondent device. The error correction encoder generates encoded data by performing an error correction encoding on transmission data using the error correction scheme determined by the error correction scheme determining unit. The modulation format determining unit determines a modulation format based on the error correction scheme determined by the error correction scheme determining unit and transmission characteristics between the optical transmission device and the correspondent device. The optical transmitter generates a modulated optical signal from the encoded data with the modulation format determined by the modulation format determining unit.

Abstract: The present disclosure discloses a method and a communication system for time synchronization. The system includes at least one base station, an optical line terminal OLT, and a fiber for transmitting information between the base station and the OLT. The system further includes a clock synchronization server, configured to transmit synchronization data between the clock synchronization server and the at least one base station, so that time synchronization is implemented between the at least one base station and the clock synchronization server. According to the solutions provided by the present disclosure, the system apparatus is simple, and the cost low.

Abstract: A method for increasing energy in a pulse optical beam is provided. The method may include: receiving an optical input beam having a period pulse train with a given repetition frequency; splitting the input beam into N optical signals; phase modulating each signal in the N optical signals at a different phase, such that the N optical signal are orthogonal to each other; and coherently combining each of the phase modulated signals into a single optical output beam.

Abstract: An optical transmitting apparatus includes: a substrate; optical modulators that are arranged in parallel to one another on the substrate and modulate light; waveguides that are formed on the substrate and guide signal light represented by at least one of modulated light beams obtained by the light being modulated by the plurality of optical modulators and monitor light represented by at least another one of the modulated light beams other than the signal light; lenses that collimate the signal light and the monitor light emitted from the waveguides; and a holding member that causes the signal light and the monitor light to be emitted from the lenses in mutually-different directions, by holding the lenses in such a manner that the optical axis of at least one of the lenses is out of alignment in a predetermined direction with the optical axis of at least one of the waveguides.

Abstract: A transmitting apparatus and a receiving apparatus for visible light communication, and a visible light communication system are provided. The visible light communication system includes a transmitting apparatus and a receiving apparatus. The transmitting apparatus includes two transmitting modules. The transmitting modules include a plurality of visible light sources and a transmitting polarization plate. Polarizations of the two transmitting polarization plates are orthogonal to each other. The receiving apparatus includes two receiving modules. The receiving modules include a plurality of light detecting diodes and a receiving polarization plate. Polarizations of the paired receiving polarization plate and transmitting polarization plate are the same.

Abstract: In some implementations, the output of a directly modulated laser (DML) includes nonlinearities with respect to the input signal driving the DML. When the DML is transmitting an amplitude modulated signal, the nonlinearities can induce noise into the signal, which makes it difficult for a receiving node to correctly decode the received signal. The system and methods described herein pre-correct the error caused by the nonlinearities of the DML by filtering (or pre-correcting) the data signal that drives the DML.

Abstract: An optical signal transmitting system, comprising: an optical transmitter including one or more input terminals and an output terminal; and a temporal polarization interleaver including an input terminal and an output terminal, wherein the output terminal of the optical transmitter is communicatively coupled to the input terminal of the temporal polarization interleaver, wherein: the optical transmitter is configured to receive one or more input signals through its one or more input terminals, generate an output signal using the one or more input signals, the output signal including a x-polarized tributary and a y-polarized tributary that is pulse-to-pulse aligned with the x-polarized tributary, and transmit the output signal to the temporal polarization interleaver; and the temporal polarization interleaver is configured to receive the output signal from the optical transmitter and cause a predefined phase delay to one of the x-polarized tributary and the y-polarized tributary.

Abstract: An optical delay device includes an optical path in which an input optical signal travels the same path recursively; an optical switch that switches between an output state of outputting the optical signal input to the optical path, and a non-output state of not outputting the optical signal input to the optical path; and a controller that sets the optical switch to the non-output state until a point in time when a given delay time elapses since input of the optical signal to the optical path and at the point in time when the given delay time elapses, switches the optical switch to the output state.

Abstract: A de-emphasis format signal generator can be configured to combine first and second electrical non-de-emphasis formatted signals provided to first and second optical modulators, coupled in parallel with one another, to provide a combined optical signal having a de-emphasis format. Accordingly, three aspects of a de-emphasis formatted signal, including a de-emphasis delay aspect, a de-emphasis attenuation aspect, and a de-emphasis combining aspect, can provided separately and in different domains (such as in the electrical domain and in the optical domain) which can be combined with one another to provide an output de-emphasis formatted optical signal.

Abstract: An optical transmission system includes a polarization multiplexing optical transmitter for transmitting an optical signal, where an X-polarized signal and a Y-polarized signal each having a having predetermined frame structure are polarization-multiplexed, to an optical fiber transmission path, and a polarization multiplexing receiver for receiving the optical signal that has propagated through the optical transmission path. The polarization multiplexing optical transmitter delays a frame assignment signal (FAS) in the Y-polarized signal, by a predetermined delay time ?, relative to FAS in the X-polarized signal.

Abstract: The present invention discloses a method and system for accurate time transfer in PON. An Optical Line Terminal (OLT) ranges Optical Network Units (ONUs) and obtains ranging information, then, triggered by the periodic Pulse per n Second (PPnS), generates a PPnS timestamp based on the local reference counter and the Time of Day (TOD) above second; OLT transmits the ranging information, the periodic PPnS timestamp and TOD to ONUs; ONUs predicts the time of the next second according to said periodic PPnS timestamp, TOD and ranging information, and outputs the corresponding PPnS. The invention is characterized by the combination of the features of PON point to multi-point and PON ranging into its time transfer method, the high accuracy of time transfer, and the low hardware costs for OLT and ONU, as well as the extremely small bandwidth occupancy.

Abstract: One or more devices of a network having asymmetric delay are configured to participate in time synchronization protocol sessions in which a client device synchronizes its local clock to a master device. In one example, a system includes an optical line terminal configured to receive a time synchronization protocol packet from a grandmaster clock and an optical network unit (ONU) configured to calculate a residence time of the time synchronization protocol packet, encode the residence time into the packet, and to forward the packet to a client device. Moreover, the system may participate in a plurality of time synchronization protocol sessions with a plurality of client devices, such that the client devices become synchronized in frequency and phase.

Abstract: In a communication system using a PON, time synchronization of a slave device such as a base station is realized with respect to a master device such as an L2SW or the base station. Time information acquired by a GPS satellite is corrected by ranging information of a discovery function of an OLT so as to be reflected on time information of each ONU. A propagation delay from the L2SW to the OLT is obtained with the use of a delay estimation mechanism, a propagation delay from the OLT to the ONU which is obtained by ranging is added to obtain a propagation delay from the L2SW to the ONU. The obtained propagation delay from the L2SW to the ONU is added to the transmitted time stamp value whereby a time stamp value received at a base station or femtocell side becomes a time into which the propagation delay to the ONU is incorporated, and absolute values of clock timers can be synchronized with each other.

Abstract: An optical fiber network comprises a laser source (1a) configured to generate laser light of a plurality of wavelengths. A first optical fiber (4a), transmits multi-wavelength light from the laser source to a location remote from the laser source. A wavelength division multiplexer (2) at the remote location (203) is connected to a plurality of second optical fibers (8). A plurality of optical modulators (9) are each connected optically to the wavelength division multiplexer (2) via a respective second optical fiber (8). The wavelength division multiplexer (2) is arranged to de-multiplex the multi-wavelength light received from the first optical fiber (4a) into a plurality of wavelengths and to supply a respective wavelength to each of the second optical fibers (8). The optical modulators (9) are reflective optical modulators each arranged to modulate light received from the associated second optical fiber (8) with a data signal and to reflect the modulated light back along the second optical fiber (8).

Abstract: In a PON system in which communication is performed at a plurality of types of transmission rate (L, M, and H) in an upstream direction from a plurality of terminals connected to a station apparatus through optical fibers, within a discovery period for allowing an unregistered terminal to be recognized by station apparatus, the terminal makes a discovery response at one type of transmission rate (L). With this configuration, station apparatus can wait for a discovery response with a receive function being allowed to support transmission rate (L).

Abstract: An optical transmitter includes: a pre-compensator calculating an electrical field of an optical signal subjected to an electronic pre-compensation with respect to an input digital signal; a parallelizer parallelizing the electrical field of the optical signal calculated by the pre-compensator; a plurality of optical modulators modulating an optical signal based on each of parallelized electrical fields of optical signals; and a time-division multiplexer time-division-multiplexing an optical signal output from the plurality of the optical modulators.

Abstract: A method for monitoring a passive optical network (1), PON, having a tree-like structure with a main line (3) and at least two branches (6.1 to 6.3), comprising: transmitting a wake-up signal (10) from the main line (3) to at least two monitoring units (DPM1 to DPM3) arranged in the at least two branches (6.1 to 6.3), in each of the monitoring units (DPM1 to DPM3), detecting the wake-up signal (10) and transmitting a response signal (A, B, C) back to the main line (3), each of the monitoring units (DPM1 to DPM3) generating a pre-defined time delay (?tA to ?tC) between the detection of the wake-up signal (10) and the start of the transmission of the response signal (A, B, C), and receiving the response signals (A, B, C) at the main line (3), the receiving times (R1 to R3) of the response signals (A, B, C) being different from each other, the difference between the receiving times (R1 to R3) being adjusted by the pre-defined time delays (?tA to ?tC) of the monitoring units (DPM1 to DPM3).

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 method for controlling delay in a Passive Optical Network (PON) is applicable when a Precision Timing Protocol (PTP) message is transmitted in a downlink direction. The method includes obtaining a buffer duration of the PTP message destined for an Optical Network Unit (ONU), storing the PTP message destined for the ONU, and sending the PTP message to the ONU when a duration for storing the PTP message reaches the buffer duration.

Abstract: In a PON system in which communication is performed at a plurality of types of transmission rate (L, M, and H) in an upstream direction from a plurality of terminals connected to a station apparatus through optical fibers, within a discovery period for allowing an unregistered terminal to be recognized by station apparatus, the terminal makes a discovery response at one type of transmission rate (L). With this configuration, station apparatus can wait for a discovery response with a receive function being allowed to support transmission rate (L).

Abstract: An optoelectronic timing system includes an optical timing compensation system in which optical pulses developed by a semiconductor laser are advanced or retarded based upon an expected arrival time. 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 directed into an advancing path or a retarding path by optical switches which compare an expected arrival time of a new pulse to an expected arrival time based on a previous pulse. The optical compensation system is incorporated into a precision timing device in which multiple optical paths, having decreasing lengths in a defined pattern, are arranged in serial fashion so as to have each subsequent path of the series represent a travel time one order of magnitude different than a travel time of an adjacent path.

Abstract: In communications where synchronization of optical signals containing data is required, a multi-channel optical arrayed time buffer may be used. The time buffer includes multiple delay paths comprising delay elements, some of which can be shared to dispense different delays. In an embodiment, an arrayed waveguide grating (AWG) is illustratively used to route an optical signal to a first delay path, which is returnable to the AWG through the first delay path to be rerouted to a second delay path. The total delay affordable to the optical signal is a function of at least a first delay afforded by a delay element in the first delay path, and a second delay afforded by a delay element in the second delay path. In addition, without returning to the AWG, another optical signal may be routed through the second delay path alone to be afforded the second delay only.

Abstract: The present invention provides a method of generating time-division multiplexed encoded transmission signals, including encoding optical pulse signals for each of a plural multiplexed channels and generating a transmission signal for each channel, performing time division multiplexing on first and second transmission signals and generating a 2-channel multiplexed signal modulating the multiplexed signal with a modulation signal having a frequency of (F??f) Hz, detecting a strength of a ?f Hz frequency component of the multiplexed signal changing a time delay amount of the second transmission signal with respect to the first transmission signal, and determining a time delay amount at which a strength of the ?f Hz frequency component is minimized and adjusting the transmission signals of the individual channels such that they are arranged at equidistant intervals on a time axis.

Abstract: An optical transmission apparatus communicable with a plurality of subscriber including a delay measuring part for detecting a response delay time from each subscriber based on reception timing of the delay measurement response optical packet, a detection part for detecting a received optical level of the delay measurement response optical packet received by the reception part and a state determination part for determining quality of an optical transmission state between the optical transmission apparatus and each subscriber based on the received optical level of the delay measurement response optical packet of each of the plurality of subscribers.

Abstract: In a PON system in which communication is performed at a plurality of types of transmission rate (L, M, and H) in an upstream direction from a plurality of terminals connected to a station apparatus through optical fibers, within a discovery period for allowing an unregistered terminal to be recognized by station apparatus, the terminal makes a discovery response at one type of transmission rate (L). With this configuration, station apparatus can wait for a discovery response with a receive function being allowed to support transmission rate (L).

Abstract: An apparatus includes an oscillator circuit configured to generate a certain oscillation signal, an adder configured to add the oscillation signal to the tap coefficient of any of one or more taps of the transversal filter, a signal-quality measurer configured to measure a signal quality of a signal output from the transversal filter, and a tap-coefficient adjuster configured to control the value of the tap coefficient so that an optimal amount of shift in the signal quality of the output signal is achieved when the oscillation signal is added to the tap coefficient.

Abstract: A de-emphasis format signal generator can be configured to combine first and second electrical non-de-emphasis formatted signals provided to first and second optical modulators, coupled in parallel with one another, to provide a combined optical signal having a de-emphasis format. Accordingly, three aspects of a de-emphasis formatted signal, including a de-emphasis delay aspect, a de-emphasis attenuation aspect, and a de-emphasis combining aspect, can provided separately and in different domains (such as in the electrical domain and in the optical domain) which can be combined with one another to provide an output de-emphasis formatted optical signal.

Abstract: A passive optical network system (PON) has a plurality of OLTs and ONUs with different transmission rates. OLTs with different transmission rates share information of priority frames and destinations, and determine timing for frame transmission to ONUs so that the signal from each of the OLTs does not collide when multiplied in a splitter. OLTs transmit the data to the ONU as a burst signal to prevent the signals with different rates from colliding. ONU acquires the information of the following burst frames. ONU receives only the signal addressed to the own ONU or with the transmission rate of own ONU, therefore errors in ONUs can be avoided. OLT receives only the signal with the transmission rate of own OLT from ONUs based on the transmission timing from the ONUs shared by the line terminators, errors in OLTs can be avoided.

Abstract: An OLT includes a first transmitter and receiver unit for transmitting and receiving signals with ONUs, a first communication control timer, a measurement unit for measuring a round trip time (RTT) between the OLT and each of ONUs, an advance notice time generation unit for generating an advance notice time signal by adding a predetermined time to a time information that indicates a time in the first communication control timer in response to a first time reference pulse, and a unit for controlling the first transmitter and receiver unit to transmit the generated advance notice time signal to each of the ONUs, and to transmit signals indicating measured RTT/2 to the respective ones of the ONUs.

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: 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: Fully optical device for breaking down the dynamic range of an optical signal and system for measuring the signal, using this device. This device comprises fully optical means to break down this dynamic range.

Abstract: A method of determining an optical distance between two nodes of an optical network for chromatic dispersion compensation includes using existing optical supervisory channel components in each node to measure the “time-of-flight” of an optical signal having a known wavelength. The effective optical distance is determined based on the time-of-flight and known wavelength of the optical signal. The computed optical distance may then be used to compensate for the dispersion experienced by the optical signal when transmitted between the two nodes. Advantageously, the method allows tunable dispersion compensation of a wavelength channel to be periodically optimized at each node in response to incremental changes in environmental factors that affect the chromatic dispersion produced between the two nodes or in response to reconfigurations that affect the chromatic dispersion produced between the two nodes.

Abstract: According to one embodiment, a multiplex delay unit comprises an optical all-pass filter (OAPF) adapted to apply continuously tunable group delay to a wavelength division multiplexing (WDM) signal so that all of its WDM components are delayed by substantially the same delay time. The OAPF has a free spectral range (FSR) that matches spectral separation between carrier wavelengths of the WDM signal. Advantageously, an optical multiplex synchronizer suitable for feeding a synchronous optical switch fabric can be implemented as an integrated waveguide circuit using a plurality of such multiplex delay units.