Abstract: A chromatic dispersion compensator of present invention includes a high-refractive-index VIPA plate, a three-dimensional mirror, and a control unit. The high-refractive-index VIPA plate is made of a material such as silicon having a refractive index higher than that of optical glass and is able to output incident lights toward different directions according to wavelength. The three-dimensional mirror reflects the light of each wavelength emitted from the high-refractive-index VIPA plate, at a predetermined position and returns the light to the VIPA plate. The control unit controls a temperature of the high-refractive-index VIPA plate at a constant level while controlling the position of the three-dimensional mirror corresponding to a chromatic dispersion compensation amount. Thereby, larger chromatic dispersion can be compensated while a decrease in transmission bandwidth is suppressed.

Abstract: An open-path optical communication system has either optical or laser sources and communicates between the source and a detector. In a first embodiment, the laser source includes a gas cell in the laser cavity to regulate laser wavelengths based on the minimum absorption between spectral lines of the gas in the cell. The laser is tuned close to a minimum absorption wavelength and the minimum absorption line locks the laser wavelength to the minimum position. In a second embodiment, the strong absorption lines of a gas in a gas cell positioned at a receiver site are used to provide channel isolation of the receiver. In a third embodiment, an atmospheric gas provides the channel isolation. In the fourth embodiment, individual wavelength channels are positioned between the absorption lines of atmospheric or non-atmospheric gases to prevent cross-talk between adjacent channels.

Abstract: The present invention relates to an optical modulator that generates quaternary amplitude modulated light without inter-symbol-interference by splitting input light into three optical paths, generating a continuous wave signal in a first optical path, generating binary phase modulated lights using a single drive MZ type optical phase modulator in second and third optical paths, and interfering them at in-phase and at field amplitude 1:a:b.

Abstract: A timing jitter measurement system and method is provided that acquires the timing jitter in an all-optical fashion, by extracting the timing jitter probability distribution function using auto-correlation and cross-correlation data. This makes the system and method of the present invention particularly useful for ultra-high bit rates, where power spectrum analysis cannot be applied. The resolution of the timing jitter measurement system and method is higher than the actual pulse width, and depends on the time resolution of the correlator. The system and method of the present invention facilitates the identification of deterministic or random timing jitters or combinations thereof, and therefore can be used to identify the origins of timing jitters within the optical network and to provide feedback to the optical network that can be used to actively control the timing jitter.

Abstract: A distortion circuit is provided for correcting the distortion from a nonlinear circuit element by generating a frequency dependent signal having a sign opposite to the distortion signal produced by the nonlinear circuit and substantially the same magnitude. The distortion circuit includes an input signal and a first nonlinear device coupled to the input signal for generating a first signal and where the first nonlinear device has a first bias level. Also included is a second nonlinear device different from same first nonlinear device and coupled to the first nonlinear device for modifying the first signal to produce an output second signal, the second nonlinear device having a second bias level. A bias control means is provided for adjusting the first and said second bias levels so that the magnitude, phase and frequency of the output second signal can be adjusted.

Abstract: An optical communication system includes an optical transmission apparatus and an optical receiving apparatus. The optical transmission apparatus includes an input port to receive an electric signal, a noise generator to generate noise, a transmission signal generator to generate a transmission signal by multiplexing the noise with the electric signal, and an electric/optical converter to convert the transmission signal into an optical signal and send out the optical signal to an optical transmission path. The optical receiving apparatus connected to the optical transmission apparatus via the optical transmission path and receiving the optical signal through the optical transmission path. The optical receiving apparatus includes an optical/electric converter to convert the optical signal received through the optical transmission path into a receive electric signal and a receiving filter to remove the noise from the receive electric signal.

Abstract: An optical fiber device converts an input optical pulse having a predetermined center wavelength into an optical pulse having a wavelength bandwidth broader than that of the input optical pulse. The optical fiber device includes a plurality of optical fibers connected in a cascaded manner each having negative wavelength dispersion at the center wavelength. The optical fibers have different relative refractive index differences between a core region and a cladding region from each other. The optical fibers are connected such that wavelength dispersions of adjacent optical fibers at the center wavelength are different from each other.

Abstract: A hybrid IR transmission system implements at least two IR transmission protocols with a common IR transceiver. The hybrid IR transmission system includes an IR decoding circuit, a common IR transceiver and a filter circuit. The IR decoding circuit includes an IrDA module for decoding IR signals in IrDA protocol and a CIR module for decoding IR signals in CIR protocol. The common IR transceiver receives a first IR signal in either IrDA or CIR protocol. The filter circuit processes the first IR signal into a second IR signal accessible to one of the IrDA module and the CIR module for decoding.

Abstract: A method of recovering a clock signal from an optical signal received through an optical communications system. A digital sample stream is processed to generate a dispersion compensated signal. The dispersion compensated signal is then tapped to obtain upper side band and lower side band signals of each received polarization of the optical signal. The upper side band and lower side band signals are then processed to compensate polarization dependent impairments, and the clock recovered from the resulting optimized.

Abstract: Optical networks as defined by the IEEE 802.3ah standard suffer from Stimulated Raman Scattering (SRS) that causes data transmission at a first optical wavelength to interfere with broadcast video transmission at a second optical wavelength in single mode optical fibers. The problem is exacerbated when data is not being transmitted across the network; and instead, an idle pattern transmission is being transmitted in order to keep the network synchronized. The repetitive nature of the idle pattern transmission leads to the SRS optical interference effect. This optical interference effect is mitigated when countermeasures are implemented to modify the idle pattern transmissions or to transmit random data in place of the idle pattern transmissions.

Abstract: A method of operating an optical transmission system is described. The transmission system is provided with a bit-to-bit polarization interleaved bitstream having a given bitrate. The transmission system comprises a birefringent element and/or a decision circuit. The birefringent element and/or the decision circuit are triggered by a trigger signal having a frequency of half of the bitrate.

Abstract: An amount of change of a control signal applied to a polarization controller in a polarization mode dispersion compensator is determined for each feedback loop by evaluating degree of polarization response in past feedback loops.

Abstract: A dispersion compensator (1) has a substrate (2) made of a resin, on which a conductor layer (3a), a dielectric layer (4a), a wiring layer (5a), a dielectric layer (4b), a wiring layer (5b), a dielectric layer (4c), and a conductor layer (3b) are provided in this order. A transmission line (6a) forming the wiring layer (5a) and a transmission line (6b) forming the wiring layer (5b) have identical shapes to each other and have equivalent dispersion characteristics to each other. The transmission lines (6a) and (6b) are formed in a meander shape and are arranged to overlap with each other as viewed in plan. Differential signals (14) and (15) are input to the transmission lines (6a) and (6b), respectively.

Abstract: A method of carrier recovery from a high speed optical signal received through an optical communications network. A stream of multi-bit digital samples of the optical signal is processed to generate a multi-bit estimate X?(n) of each one of a plurality of transmitted symbols. A phase of each symbol estimate X?(n) is rotated, and a respective symbol phase error ??(n) of the rotated symbol estimate determined.

Abstract: A method of initializing an optical communication link between nodes. Optical transmitters adapted to pre-compensate link impairments based upon an optical compensation parameters are utilized to establish an optical communications link. Pre-compensation parameter values are selected at a node for generating an optical signal. The value is selected until confirmation from the remote node is received that the optical signal transmission has been successful. The successful pre-compensation parameter value is then used to generate the optical signal for the communications link.

Abstract: An optical transmission system capable of efficiently reducing waveform distortion of an optical signal. A transmitting-side distortion compensation coefficient storage of a transmitting station stores transmitting-side distortion compensation coefficients for compensating for waveform distortion of an optical signal to be transmitted to a receiving station. A transmit signal processor performs distortion compensation on the optical signal on the basis of a suitable transmitting-side distortion compensation coefficient stored in the transmitting-side distortion compensation coefficient storage. A transmitter transmits the distortion-compensated signal to a transmission path. A receiver of the receiving station receives the optical signal from the transmission path. A receiving-side distortion compensation coefficient storage stores receiving-side distortion compensation coefficients for compensating for waveform distortion of the optical signal received by the receiver.

Abstract: A scheme is described for mitigating the effects of polarization-mode dispersion (PMD) in a wave-division multiplex (WDM) optical communication system having one or more transmission links with one or more quasi-static waveguide sections coupled by one or more non-static coupling sections. A transmitter is coupled to the transmission link and is adapted to transmit optical signals through the transmission link with wavelength channel spacing of the optical signals greater than about the PMD correlation bandwidth of at least one of the one or more quasi-static waveguide sections, so that the PMD induced outage probability for the system is optimized.

Abstract: Disclosed are systems and methods for improving communication in an optical communication system having spectrally shaped pulses. Embodiments of the systems and methods include sending a first spectrally shaped pulse over a channel connecting a transmitter and a receiver. Then, comparing the spectrally shaped pulse received at the receiver to a predetermined spectrally shaped pulse. The systems and methods further include obtaining a preemphasis coefficient that describes the difference between the spectrally shaped pulse received at the receiver to the predetermined spectrally shaped pulse by utilizing a mathematical description of C(?k)ej(??(?k)) and multiplying a second spectrally shaped pulse with the preemphasis coefficient before sending the second spectrally shaped pulse to the receiver.

Abstract: A system and method for increasing transmission distance and/or transmission data rates using tedons and an encoding scheme to reduce the number of ones in a data signal is described. For example, the method for increasing transmission distance and transmission data rate of a fiber optical communications link using tedons includes the steps of encoding a data signal to be transmitted using an encoding scheme that reduces a number of ones in the data signal, transmitting the encoded data signal over the fiber optical communications link, receiving the encoded data signal and decoding the encoded data signal.

Abstract: This device for optically regenerating pulses includes a synchronous intensity modulator to provide time synchronization for pulses passing through it and to stabilize intensity fluctuations in the pulses. In addition, it includes noise suppression circuitry in the form of a saturable absorber that is distinct from the synchronous intensity modulator and the intensity fluctuations stabilizer.

Abstract: A dispersion compensation system includes a dispersion compensation module and a dispersion enhancement module. The dispersion compensation module receives optical input and provides optical output having a negative dispersion relative to the optical input. The dispersion enhancement module receives optical signals from a transport fiber and may increase positive dispersion in the optical signals by a configured amount such that the positive dispersion provided by the transport fiber and the dispersion enhancement module substantially equals the magnitude of the negative dispersion provided by the dispersion compensation module.

Abstract: An optical receiver includes closed-loop composite second order (CSO) distortion correction logic. An optical communication system includes a transmitter comprising open-loop composite second order (CSO) distortion correction logic, and a receiver comprising closed-loop composite second order (CSO) distortion correction logic.

Abstract: An electronic dispersion compensation (EDC) arrangement for a multi-channel optical receive utilizes a time division technique to “share” a common adaptive algorithm block between a plurality of N separate channels. The algorithm block embodies a specific algorithm associated with correcting/updating tap weights for the delay lines forming the equalizing elements, and a time slot assignment element is used in conjunction with the algorithm block to control the access of the various channels to the algorithm block. In situations where certain channels experience a greater degree of dispersion than others, the time slot assignment element may be configured to allot a greater number of time slots to the affected channels.

Abstract: Techniques and system implementations for fiber optic transmission systems for suppressing fiber induced distortions and modulation-induced distortions as well as increasing the link power and RF gain.

Abstract: A system for dispersion compensation in a terahertz system includes an optical fiber configured to transmit an optical pulse, a compensator optically coupled to the optical fiber, the compensator configured to compensate for a dispersion of the optical pulse caused as the optical pulse propagates through the optical fiber, and an optically induced terahertz device optically coupled to the compensator, whereby the optically induced terahertz device is configured to transmit or receive terahertz radiation.

Abstract: An optical apparatus comprises a phase comparator detecting a phase shift between a changing point of data transmitted through an electro/opto converter and a changing point of data received through an opto/electro converter, a delay controller and a variable delay circuit controlling a delay of the transmitted data so that the phase shift detected becomes equal to a value which minimizes a receiver sensitivity degradation due to crosstalks between a transmitter portion and a receiver portion.

Abstract: A method and apparatus for providing diagnostic features for an optical transceiver, in which the optical transceiver uses electronic dispersion compensation (EDC) in order to alleviate distortion of a signal caused by dispersion. A method and apparatus for monitoring the performance of an electronic dispersion compensator by monitoring one or more signals from the electronic dispersion compensator and generating an alarm in the vent that the performance of the electronic dispersion compensator falls below a certain threshold.

Abstract: An optical network route and method are disclosed that mitigate distortion in a route having different types of fibers. For an optical network route that includes a plurality of fiber spans of a first type and a fiber span of a second type, assume that the optical network route is transporting optical signals having a plurality of original wavelengths where one or more of the original wavelengths is in a distortion wavelength region of the second type of fiber span. For optical signals entering the second type of fiber span, the original wavelength that is in the distortion wavelength region of the second type of fiber span is shifted to a temporary wavelength outside of the distortion wavelength region. The optical signals then travel over the second type of fiber span. For optical signals exiting the second type of fiber span, the temporary wavelength is shifted back to the original wavelength.

Abstract: A method and system for controlling optical signal to noise ratio (OSNR) of an optical signal at a receiver end of an optical link. A multi-bit sample stream is generated using a compensation function adapted to compensate impairments of the optical link A digital noise signal is generated and added to the multi-bit sample stream, and the resulting signal used to generate a degraded optical signal, which is then transmitted through the optical link.

Abstract: A dispersion compensation method and a fiber transmission system are disclosed, pertaining to the field of fiber communications. The dispersion compensation method includes: after performing electrical pre-compensation processing on a digital transmit signal, the transmitting end controls the electrical/optical converting module to output a distorted optical signal; after receiving the optical signal, the receiving end performs post-compensation processing after converting the optical signal into an electrical signal, or converts the optical signal into an electrical signal after performing post-compensation processing on the optical signal. The fiber transmission system includes: a pre-compensation signal processing module, an optical source, an electrical/optical converting module, a fiber transmission line, an optical/electrical converting module, and a post-compensation processing module.

Abstract: An optical communication system and a communication network are disclosed herein capable of transmitting optical signals with high optical launch power over unrepeatered optical fiber links. A method of transmitting optical signals is also disclosed herein which comprises transmitting optical signals at high optical launch power over unrepeatered links.

Abstract: A method of controlling optical signal traffic in an optical network between a transmitter and a plurality of receivers, where the transmitter is adapted to compensate optical impairments based on at least one optical parameter, includes steps of identifying each path between the transmitter and the plurality of receivers, determining a respective optical parameter for each path, selecting one of the receivers for receiving an optical signal from the transmitter, and enabling the transmitter to generate the optical signal using the respective optical parameter of the path between the transmitter and the selected receiver. By preconfiguring compensation parameters for the various paths in the network, an all-optical network can be implemented wherein optical signals can be switched, added or dropped without having to match dispersion maps or perform optical-electrical-optical regeneration.

Abstract: An optical equalizer/dispersion compensator (E/CDC) comprises an input/output for receiving a multiplexed channel signal comprising a plurality of channel signals of different wavelengths. An optical amplifier may be coupled to receive, as an input/output, the multiplexed channel signals which amplifier may be a semiconductor optical amplifier (SOA) or a gain clamped-semiconductor optical amplifier (GC-SOA). A variable optical attenuator (VOA) is coupled to the optical amplifier and a chromatic dispersion compensator (CDC) is coupled to the variable optical attenuator. A mirror or Faraday rotator mirror (FRM) is coupled to the chromatic dispersion compensator to reflect the multiplexed channel signal back through these optical components The E/CDC components may be integrated in a photonic integrated circuit (PIC) chip.

Abstract: Dispersion compensation values are set so as to be transmittable to any path groups in a WDM optical communication system having OADM nodes, which includes transmitting-end and receiving-end terminal nodes; a WDM optical communication transmission line including a plurality of spans each having an optical fiber, the plurality of spans joining the transmitting-end and receiving-end terminal nodes; and a plurality of add drop multiplexing (OADM) nodes disposed on the optical communication transmission line; wherein when taking as the reference a residual dispersion target value of between the transmitting-end terminal and receiving-end terminal nodes, a residual dispersion target value for a node segment between one of the terminal nodes and one of the add drop multiplexing (OADM) nodes and a residual dispersion target value for a node-to-node segment between two of the add drop multiplexing (OADM) nodes are set so as to be proportional to ratios of the span counts in the node segment and in the node-to-node se

Abstract: An apparatus and method for transmitting a signal for optical network applications with automatic chromatic dispersion compensation. The apparatus includes a first optical transmitter. The first optical transmitter includes a first light source configured to generate a first laser signal in response to a first laser drive signal, a first data modulator configured to receive the first laser signal and a first data drive signal and output a first chirped return-to-zero signal, and a first signal source configured to generate a first non-return-to-zero signal. Additionally, the apparatus includes a first clock and data recovery system, a first data driver, a first adjustment system, and a first control system.

Abstract: An apparatus includes an optical transmitter having a first dynamically reconfigurable optical filter, an optical receiver having a second dynamically reconfigurable optical filter. The optical transmitter and optical receive are connected via an optical fiber transmission line. The optical filters are configured to function in a complementary manner.

Abstract: The invention relates to an optical transmission system which allows high quality transmission of signal light, and has a configuration that is suitable particularly for CWDM optical transmission. In the optical transmission system, signal channels outputted from non-temperature controlled direct modulation light sources are multiplexed by a multiplexer, transmitted through an optical fiber transmission line, and demultiplexed into a first wavelength band ?1 and second wavelength band ?2 by a demultiplexer. The signal channel group in the second wavelength band ?2 of which the absolute value of chromatic dispersion is large is dispersion-compensated for by a non-temperature controlled dispersion compensator. The chromatic dispersion of the signal channels in the second wavelength band ?2 after passing through the dispersion compensator is set to be negative over a temperature range of 0° C. to 60° C.

Abstract: A method of recovering a clock signal from an optical signal received through an optical communications system. A digital sample stream is processed to generate a dispersion compensated signal. The dispersion compensated signal is then tapped to obtain upper side band and lower side band signals of each received polarization of the optical signal. The upper side band sand lower side band signals are then processed to compensate polarization dependent impairments and the clock recovered from the resulting optimized.

Abstract: The present invention relates to optical communication apparatuses such as OADM node, or OXC node. A receiving dispersion compensating module adjusts the accumulated dispersion of a wavelength-division-multiplexed optical signal such that the accumulated dispersion has an optimum value at a receiver for receiving optical signals in respective wavelength channels which are dropped from the wavelength-division-multiplexed optical signal. An auxiliary dispersion compensating module is provided in a path for an added wavelength group. The auxiliary dispersion compensating module applies the same value of dispersion as the accumulated dispersion adjusted by the receiving dispersion compensating module, to a wavelength-division-multiplexed optical signal in the added wavelength group.

Abstract: A transmitter (11) emits a single wavelength optical signal and transmits this as a wavelength channel (13) in a compound multiplex signal through the WDM network. The receiver (12) selects the single wavelength optical signal (21) from the compound multiplex signal using a band-pass filter. A wavelength fit detector (15) determines a feedback signal by correlating variations of the amplitude of the received signal with variations of the traffic density. This feedback signal is then returned to the transmitter (11) via a back channel (16) and serves to tune the wavelength of the single wavelength optical signal.

Abstract: A method of providing dispersion compensation includes providing a dispersion signal indicative of an amount of dispersion for at least one channel of a multi-channel optical signal. A dispersion compensator is controlled in accordance with the dispersion signal to optically compensate for the dispersion of the optical signal.

Abstract: An apparatus and method directed to testing and optimizing performance of an optical transmission system is disclosed, including at least one broadband dispersion compensation unit (DCU) or at least one depolarization device. The depolarization device may be used alone or in combination with the at least one broadband DCU. A method for optimizing performance of data channels in initial loading (IL) and full loading (FL) configurations of the optical transmission system is also disclosed.

Abstract: An all optical network for optical signal traffic has at least a first ring with at least one transmitter and one receiver. The first ring includes a plurality of network nodes. At least a first add/drop broadband coupler is coupled to the first ring. The broadband coupler includes an add port and a drop port to add and drop wavelengths to and or from the first ring, a pass-through direction and an add/drop direction. The first add/drop broadband coupler is configured to minimize a pass-through loss in the first ring and is positioned on the first ring.

Abstract: A bidirectional communication system is disclosed. A single optical line amplifier is used to amplify signals in both the east and west directions. Additionally, a single dispersion compensation module is used to compensate for fiber dispersion in both directions. Using a single optical line amplifier and a single dispersion compensation module for both directions allows for reduction in the number of optical line amplifiers used in a given network.

Abstract: One embodiment of the invention relates to producing optical pulses for use on a transmission link. A light source is configured to produce an optical signal. A pulse generator is coupled to the light source. The pulse generator is configured to receive, for a first channel, the optical signal and a clock signal. The pulse generator is also configured to modify the optical signal based on the clock signal to produce an optical pulse having a predetermined pulse shape. The clock signal is associated with the predetermined pulse shape. The predetermined pulse shape being based on a transmission characteristic of the transmission link.

Abstract: An optical fiber system comprising: (i) a dispersion pre-compensator including dispersion compensating fiber DCF characterized by the overall dispersion value DDCF at the operating wavelength ?; and (ii) a passive optical network (PON) including a plurality of transmission paths provided by a plurality of optical fibers, said plurality of transmission paths having a minimum and maximum dispersion value DMIN and DMAX; wherein the dispersion pre-compensator includes an output port operatively coupled to an input port of the a passive optical network and ?DMAX<DDCF<?DMIN.

Abstract: A dispersion compensator is applicable to a WDM optical transmission system and features low loss, wideband usage, and minimum ripple. The dispersion compensator is constructed so that the light emitted from a collimator will be reflected from an etalon of a 100% single-side reflectance by arranging the etalon and a mirror in parallel or with a slight angle and then enter another collimator. Elements for achieving variable dispersion compensation by changing temperature using a heater, for example, are also provided. In addition, these dispersion compensating elements are provided in multi-stage form and the angle of the mirror and the reflectance of the etalon are optimized. Thus, it becomes possible to realize a dispersion compensator applicable to a WDM optical transmission system and featuring low loss, wideband usage, and minimum ripple.

Abstract: In order to enhance dispersion control, the apparatus includes a dispersion controller; a quality index generator generating a quality index representing a quality of an optical signal output from the dispersion controller; and a searching unit searching for an amount of dispersion control applying to the dispersion controller which amount optimizes the quality index, wherein the searching unit includes a splitting-half searching unit roughly searching, in a splitting half method, a range in which dispersion is controllable by the dispersion controller for an amount of dispersion control such that the quality index generated by the quality index generator becomes preferable, and a sweep searching unit thoroughly searching, by sweeping, a limited range based on the amount of dispersion searched by the splitting-half searching unit for an amount of dispersion control that optimizes the quality index generated by the quality index generator.

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

Abstract: The disclosed technology provides a dynamic interconnection system which allows to couple a pair of optical beams carrying modulation information. In accordance with the disclosed technology, two optical beams emanate from transceivers at two different locations. Each beam may not see the other beam point of origin (non-line-of-sight link), but both beams can see a third platform that contains the system of the disclosed technology. Each beam incident on the interconnection system is directed into the reverse direction of the other, so that each transceiver will detect the beam which emanated from the other transceiver. The system dynamically compensates for propagation distortions preferably using closed-loop optical devices, while preserving the information encoded on each beam.