Intermodulation Patents (Class 398/211)
  • Patent number: 8867931
    Abstract: A transceiver architecture for wireless base stations wherein a broadband radio frequency signal is carried between at least one tower-mounted unit and a ground-based unit via optical fibers, or other non-distortive media, in either digital or analog format. Each tower-mounted unit (for both reception and transmission) has an antenna, analog amplifier and an electro-optical converter. The ground unit has ultrafast data converters and digital frequency translators, as well as signal linearizers, to compensate for nonlinear distortion in the amplifiers and optical links in both directions. In one embodiment of the invention, at least one of the digital data converters, frequency translators, and linearizers includes superconducting elements mounted on a cryocooler.
    Type: Grant
    Filed: September 4, 2012
    Date of Patent: October 21, 2014
    Assignee: Hypres, Inc.
    Inventors: Deepnarayan Gupta, Oleg Mukhanov
  • Patent number: 8855504
    Abstract: An optical receiver has an adaptive optical compensator and/or an adaptive electrical equalizer for compensating signal distortion in a received optical signal. In order to achieve a very fast adaptation of the receiver to the actual signal distortion, which is important for example for bursts mode optical signals in a packet-switched optical transmission network, at least one predetermined trainings sequence is provided in the optical signal, which is known at the receiver and thus enables fast adaptation of the compensator and/or equalizer to the actual signal distortion.
    Type: Grant
    Filed: June 23, 2004
    Date of Patent: October 7, 2014
    Assignee: Alcatel Lucent
    Inventor: Henning Bülow
  • Patent number: 8798484
    Abstract: A technique is provided for configuring an optical receiver. A photo detector is connected to a load resistor, and the photo detector includes an internal capacitance. A current source is connected through a switching circuit to the load resistor and to the photo detector. The current source is configured to discharge the internal capacitance of the photo detector. The switching circuit is configured to connect the current source to the internal capacitance based on a previous data bit.
    Type: Grant
    Filed: February 16, 2012
    Date of Patent: August 5, 2014
    Assignee: International Business Machines Corporation
    Inventors: Jonathan E. Proesel, Alexander V. Rylyakov, Clint L. Schow, Yurii A. Vlasov
  • Patent number: 8768181
    Abstract: A differential code optical transmission and reception device including: a digital signal processing optical transceiver that converts information data into an optical signal and transmits it to a communication channel, a reception front end part that receives the optical signal from the communication channel, an O/E conversion part that converts the optical signal received from the communication channel into an electrical signal, a skew correction part that regulates or correct a skew between lanes contained in the electrical signal, a differential decoder that decodes a differential code of the skew corrected electrical signal, and a lane exchange/rotation part that rearranges the electrical signal having passed through the differential decoder into a lane state thereof at the time of transmission in cases where lane exchange has occurred in the communication channel.
    Type: Grant
    Filed: October 6, 2010
    Date of Patent: July 1, 2014
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kiyoshi Onohara, Hideo Yoshida, Takashi Sugihara
  • Patent number: 8761609
    Abstract: A receiver for fiber optic communications.
    Type: Grant
    Filed: November 2, 2010
    Date of Patent: June 24, 2014
    Assignee: ClariPhy Communications, Inc.
    Inventors: Oscar E. Agazzi, Diego E. Crivelli, Hugo S. Carrer, Mario R. Hueda, Martin I. del Barco, Pablo Gianni, Ariel Pola, Elvio Serrano, Alfredo Taddei, Alejandro Castrillon, Martin Serra, Ramiro Matteoda
  • Patent number: 8731411
    Abstract: A polarization fluctuation compensation device, when WDM light received by, for example, an optical reception device includes a polarization scrambled optical signal and a non-polarization scrambled optical signal, collects information related to whether optical signals having respective wavelengths are polarization scrambled, obtains a target value of control parameters which are different from each other, according to the speed of polarization fluctuations in the non-polarization scrambled optical signal based on the collected information, and performs reception processing of the non-polarization scrambled optical signal by using a control parameter set as the target value. As a result, an influence of fast polarization fluctuations generated resulting from an interaction between optical signals having respective wavelengths can be reliably compensated for, thereby enabling to realize excellent reception characteristics.
    Type: Grant
    Filed: March 31, 2011
    Date of Patent: May 20, 2014
    Assignee: Fujitsu Limited
    Inventors: Shoichiro Oda, Takeshi Hoshida, Toshiki Tanaka, Hiroyuki Irie, Hiroshi Nakamoto
  • Patent number: 8718491
    Abstract: In a coherent optical receiver receiving a polarization multiplexed optical signal through an optical communications network, a method of compensating noise due to polarization dependent loss (PDL). A Least Mean Squares (LMS) compensation block processes sample streams of the received optical signal to generate symbol estimates of symbols modulated onto each transmitted polarization of the optical signal. A decorrelation block de-correlates noise in the respective symbol estimates of each transmitted polarization and generating a set of decorrelated coordinate signals. A maximum likelihood estimator soft decodes the de-correlated coordinate signals generated by the decorrelation block.
    Type: Grant
    Filed: October 29, 2009
    Date of Patent: May 6, 2014
    Assignee: Ciena Corporation
    Inventors: Amir Keyvan Khandani, Han Sun, Kim B. Roberts
  • Patent number: 8687970
    Abstract: The invention relates to a system comprising an optoelectronic modulator device and demodulator device for establishing communication between optical communication systems by means of differential modulation with eight phase changes. Said system can increase the information transmission capacity by up to three times that of a system with two phase changes. The modulation formats transmittable by the system are called: NRZ-D8PSK, RZ-D8PSK, D8PSK. The invention also relates to the design of the modulator which is formed by a differential modulation precoder and optical signal phase modulators, in which the signals leaving the precoder control the phase modulators in order to perform differential modulation with eight phase changes in relation to the optical signal originating from a semiconductor laser.
    Type: Grant
    Filed: December 1, 2008
    Date of Patent: April 1, 2014
    Assignee: Instituto Tecnologico y de Estudios Superiores de Monterrey
    Inventors: Gerardo Antonio Castañon Avila, Ivan Artiz Aldaya Garde
  • Patent number: 8655195
    Abstract: The present invention relates to an average length magnitude detecting apparatus and method, and an optical coherent receiver. The average length magnitude detecting method is adopted for detecting whether an average length of an averager used by a polarization crosstalk canceling apparatus in a receiver is long or short, comprising: determining a magnitude of a residual polarization crosstalk coefficient of the receiver; and determining an index that indicates whether the average length of the averager is long or short according to the determined magnitude of the residual polarization crosstalk coefficient.
    Type: Grant
    Filed: September 23, 2011
    Date of Patent: February 18, 2014
    Assignee: Fujitsu Limited
    Inventors: Weizhen Yan, Zhenning Tao, Lei Li
  • Patent number: 8611764
    Abstract: An optical receiver module includes an optical receiver that receives and converts a plurality of optical signals depending on different polarized states into a plurality of electric signals, a bit error detector that detects a plurality of bit error rates from electric signals, a maximum value detector that detects a maximum bit error rate among bit error rates, a dispersion compensating controller that calculates a dispersion compensating value based on the maximum bit error rate, and a variable dispersion compensator that performs dispersion compensation against waveform degradation of received optical signals. Thus, it is possible to accurately search for an optimum dispersion compensating value in a transmission line susceptible to polarized dispersion. This makes it possible to stabilize dispersion compensating control on the optical receiver.
    Type: Grant
    Filed: May 23, 2011
    Date of Patent: December 17, 2013
    Assignee: NEC Corporation
    Inventor: Morihiko Ota
  • Patent number: 8565621
    Abstract: A method for detecting and measuring time skew in high-speed DP-QPSK coherent optical receivers is described.
    Type: Grant
    Filed: September 23, 2011
    Date of Patent: October 22, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Edem Ibragimov, Sunil Kumar Singh Khatana
  • Patent number: 8538271
    Abstract: An apparatus comprising an optical receiver configured to receive an optical signal, and a combined level and clock recovery circuit coupled to the optical receiver and configured to update a signal threshold and a clock phase substantially simultaneously. Also included is an apparatus comprising at least one processor configured to implement a method comprising recognizing reception of a signal, and adjusting a threshold and a clock phase associated with the signal using a rising time for the signal and a falling time for the signal. Also included is a method comprising receiving a signal, and adjusting a threshold level of the signal to establish level recovery using a clock recovery scheme.
    Type: Grant
    Filed: November 23, 2009
    Date of Patent: September 17, 2013
    Assignee: Futurewei Technologies, Inc.
    Inventor: Frank J. Effenberger
  • Patent number: 8532504
    Abstract: An adaptive-equalizer initialization system performs three functions: frequency offset estimation, taps estimation for chromatic dispersion filters, and taps initialization for an adaptive equalizer. The system contains hardware FFT and peak detector units that sense a pure tone that marks the beginning of a known, short data sequence.
    Type: Grant
    Filed: October 28, 2010
    Date of Patent: September 10, 2013
    Assignee: Opnext Subsystems, Inc.
    Inventors: Andrew Wagner, Christian Malouin, Theodore J. Schmidt
  • Patent number: 8498544
    Abstract: A method and an optical receiver compensates for an error in a phase of an optical signal in a receiver. The signal includes blocks of symbols in a sequence. Each block is decoded based on a partially phase compensated symbols, and an average phase error for the block is estimated. Forward phase compensation and backward phase compensation is performed on the block based on the average phase error, and the decoding, estimating, performing is iterated until a termination condition is satisfied to produce a phase compensated block.
    Type: Grant
    Filed: February 10, 2011
    Date of Patent: July 30, 2013
    Assignee: Mitsubishi Electric Research Laboratories, Inc.
    Inventors: Chunjie Duan, Kieran Parsons, Philip V. Orlik
  • Patent number: 8483573
    Abstract: An optical signal of an optical transmission part is brought into a high-speed polarization scrambling state by a polarization scrambling part, and transmitted to en optical fiber transmission line as the optical signal from the optical transmitter. The optical signal passing through the optical fiber transmission line is inputted to an optical receiver. The optical signal inputted to the optical receiver is converted into an electric signal by a polarization dependent photoelectric detection part. The converted electric signal is inputted to a digital signal processing part having a polarization scrambling cancel part of canceling the polarization scrambling state by a digital signal processing operation. At the digital signal processing part, the polarization scrambling state of the electric signal is canceled, and a data signal is outputted.
    Type: Grant
    Filed: January 10, 2011
    Date of Patent: July 9, 2013
    Assignee: Hitachi, Ltd.
    Inventors: Hideaki Kotake, Nobuhiko Kikuchi, Kohei Mandai
  • Patent number: 8463140
    Abstract: A reception device includes at least a light receiving unit, a phase calculation unit, and a demodulation unit. The light receiving unit receives intensity-modulated light from a transmission device. The transmission device executes phase modulation to a bit stream as an object to be transmitted and emits the intensity-modulated light which has an intensity changing at a preset time cycle and a phase changing in response to the phase modulation, and the phase is maintained during M cycles. The phase calculation unit detects the intensity of the intensity-modulated light p times per cycle of the intensity-modulated light and repeatedly calculates the phase of the intensity-modulated light on the basis of a result of the detection. The demodulation unit executes demodulation, which corresponds to the phase modulation, to the phase calculated by the phase calculation unit, and generates transmitted bit stream.
    Type: Grant
    Filed: February 18, 2010
    Date of Patent: June 11, 2013
    Assignee: Honda Motor Co., Ltd.
    Inventor: Chiaki Aoyama
  • Patent number: 8442406
    Abstract: The present invention relates to filter, coherent receiver device and coherent receiving method. The filter is used for converting a partial response signal into a full response signal, wherein the filter uses the following transfer function HPre-Filter(z) with respect to a partial response signal having a transfer function H PR ? ( z ) = A ? ( 1 + z - 1 ) m ? ( 1 - z - 1 ) n : ? ? H Pre - Filter ? ( z ) = 1 A ? ( 1 + ? ? ? z - 1 ) m ? ( 1 - ? ? ? z - 1 ) n , in which A is other item, m and n are integers larger than or equal to 0 but not being 0 at the same time, 0<?<1.
    Type: Grant
    Filed: February 4, 2011
    Date of Patent: May 14, 2013
    Assignee: Fujitsu Limited
    Inventors: Jianqiang Li, Huijian Zhang, Zhenning Tao, Takahito Tanimura
  • Patent number: 8396375
    Abstract: A method for enabling bidirectional data communication using a single optical carrier and a single laser source with the aid of an integrated, colorless demodulator and detector for frequency modulated signals, and a reflective modulator. A receiving optical system holds a technique for demodulation and detection of optical frequency modulated signals, enabling remodulation of the incoming signal to establish bidirectional communication with the transmitting optical system, without introducing a high penalty. A colorless demodulator and detector, which provides the functionality of a periodic filtering device for demodulation of the downstream, and also detection capability. The principle of operation of the CDD relies on the introduction of a comb transfer function with the help of a Semiconductor Optical Amplifier, by providing a reflected feedback signal to the CDD's active element.
    Type: Grant
    Filed: February 18, 2010
    Date of Patent: March 12, 2013
    Assignee: Universitat Politecnica de Catalunya
    Inventors: Bernhard Schrenk, José Antonio Lázaro Villa, Christophe Kazmierski, Josep Joan Prat Gomà
  • Patent number: 8326160
    Abstract: A dispersion compensation device includes: an optical branching unit to branch an optical signal to be received; a first dispersion compensator to perform dispersion compensation on one part of the optical signal branched by the optical branching unit with a variable compensation amount; a second dispersion compensator to perform dispersion compensation on another part of the optical signal branched by the optical branching unit; a monitoring unit to monitor the communication quality of an output optical signal of the second dispersion compensator; and a controlling unit to determine the direction of variation in chromatic dispersion of the optical signal based on the direction of variation in communication quality monitored by the monitoring unit and control the compensation amount of the first dispersion compensator based on the result of the determination.
    Type: Grant
    Filed: November 22, 2010
    Date of Patent: December 4, 2012
    Assignee: Fujitsu Limited
    Inventors: Makoto Murakami, Toshihiro Ohtani
  • Patent number: 8326159
    Abstract: Systems and methods of compensating for transmission impairment over an optical transmission channel are disclosed. The optical transmission channel includes an optical fiber and an optical amplifier. One such method includes: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and solving a non-linear Schrödinger equation (NLSE) using a split-step Fourier Method (SSFM). The NLSE describes a virtual optical fiber corresponding to the optical fiber. The SSFM implements a linear operator with a wavelet-based FIR filter.
    Type: Grant
    Filed: March 19, 2010
    Date of Patent: December 4, 2012
    Assignee: University of Central Florida Research Foundation, Inc.
    Inventors: Guifang Li, Gilad Goldfarb
  • Patent number: 8306440
    Abstract: The present disclosure relates to polarization diversity receiver systems and methods with polarization mode dispersion mitigation through processing. Specifically, the present invention includes a direct-detection receiver system that removes the requirement for a LO and an ADC thereby improving power, size, and cost over existing solutions, while at the same time allowing sufficient electronic processing to mitigate PMD impairment. The present invention can be realized in a processing block in CMOS technology front-ended with a polarization diversity receiver utilizing a 90 deg. optical hybrid.
    Type: Grant
    Filed: August 6, 2009
    Date of Patent: November 6, 2012
    Assignee: Ciena Corporation
    Inventor: Michael Y. Frankel
  • Patent number: 8301040
    Abstract: An optical transmission system using Raman optical amplification, which is configured in a WDM-PON topology where a signal light between an optical line terminal and each of optical network units is multi/demultiplexed at a WDM. The optical line terminal supplies continuous lights having wavelengths to the optical network units through an optical fiber from the optical line terminal. The continuous lights are used for an uplink signal. In addition, the optical line terminal outputs a pumping light having a wavelength which is used to excite lights of the continuous lights, to the optical fiber from the optical line terminal.
    Type: Grant
    Filed: June 11, 2009
    Date of Patent: October 30, 2012
    Assignees: Fujikura Ltd., Shibaura Institute of Technology
    Inventor: Norio Kashima
  • Patent number: 8218977
    Abstract: An optical device includes an interferometer for a received optical differential phase shift keying DPSK signal, and an equalizer integrated with the interferometer in a manner for reducing from optical filtering effects an interference by signal bits of the DPSK signal with signal bits of a contiguous DPSK signal. The interferometer is a Michelson delay interferometer type, but can also be a Mach-Zehnder delay interferometer type on fiber, waveguide or other optical structure. The equalizer is a Fabry-Perot type equalizer, but can be a ring resonator type or a fiber based equalizer.
    Type: Grant
    Filed: March 25, 2010
    Date of Patent: July 10, 2012
    Assignee: NEC Laboratories America, Inc.
    Inventors: Philip Nan Ji, Lei Xu, Ting Wang, Shuji Murakami, Tsutomu Tajima, Yutaka Yano
  • Patent number: 8155535
    Abstract: An optical receiver for stably reproducing packets having different light receiving levels is disclosed. The optical receiver includes: a light receiving element for outputting a current in response to a light receiving level of an optical signal; a preamplifier for converting the current signal outputted from the light receiving element into a voltage signal; a circuit for detecting a consecutive same binary symbols portion from a binary symbols stream of the voltage signal outputted from the preamplifier to output a time constant switching signal in response to a detection result thereof; a level detecting circuit for detecting a voltage level of the voltage signal outputted from the preamplifier based upon a time constant which is switched/controlled in response to the time constant switching signal; and an amplifier for amplifying an output voltage of the level detecting circuit to apply a control voltage for controlling the gain to the preamplifier.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: April 10, 2012
    Assignee: Mitsubishi Electric Corporation
    Inventors: Masaki Noda, Masamichi Nogami, Junichi Nakagawa
  • Patent number: 8116401
    Abstract: A method and system for digital spur cancellation may include removing a spur in a left channel minus right channel (L?R) baseband signal generated from a FM signal. The L?R baseband signal may be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. An orthogonal signal may also be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. The phase of the orthogonal signal may be further adjusted to introduce a substantially ?90° phase shift to spurs at a specific frequency. Accordingly, the spurs in the L?R baseband signal may be cancelled when the first L?R baseband signal is combined with the phase adjusted orthogonal signal.
    Type: Grant
    Filed: November 22, 2005
    Date of Patent: February 14, 2012
    Assignee: Broadcom Corporation
    Inventors: Brima Ibrahim, Hea Joung Kim, Bojko Marholey
  • Patent number: 8112005
    Abstract: A receiver scheme for optical signals in Return-to-zero (RZ) systems comprises a conventional receiver at the input of which is placed an all-optical decision element realized with nonlinear optical elements. This allows obtaining a substantial increase in performance compared with a simple conventional receiver optimized for NRZ signals. In particular, an optical decision is made up advantageously of two non-linear optical loop mirrors (NOLMs) arranged in cascade with an optical amplifier at the input and a pass-band filter at the output. The loops lengths may be different, as may be the splitting ratios of the couplers of the NOLMs.
    Type: Grant
    Filed: September 28, 2006
    Date of Patent: February 7, 2012
    Assignee: Ericsson AB
    Inventors: Paolo Ghelfi, Mirco Scaffardi, Antonella Bogoni, Luca Poti
  • Patent number: 8103178
    Abstract: A phase-modulated analog optical link that uses parallel interferometric demodulation to mitigate the dominant intermodulation distortion present in the link. A receiver for demodulating phase modulated optical signals includes a splitter dividing the phase modulated signal into parallel optical paths, each optical path having an asymmetrical interferometer, the time delays of the interferometers being unequal, and each optical path includes a photodiode optically connected to an output of the interferometer. Outputs of the photodiodes enter a hybrid coupler. Alternatively, outputs of the interferometer enter a balanced photodetector. A phase shifter or time delay element can be included in one optical path to ensure inputs to the coupler or balanced photodetector have the correct phase. The input power to the parallel optical paths is split in a ratio that balances the third-order distortion in the output photocurrent.
    Type: Grant
    Filed: April 17, 2009
    Date of Patent: January 24, 2012
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Jason D. McKinney
  • Patent number: 8098994
    Abstract: Provided is an optical interconnection system that transmits and receives a three-level signal. The optical interconnection system includes a first and a second optical interconnection device that transmits and receives a two-level signal, and a synthesizer that outputs a three-level signal by synthesizing signals from the first and second optical interconnection devices. The optical interconnection system may transmit and receive a three-level signal while using an optical interconnection device that interconnects a two-level signal.
    Type: Grant
    Filed: June 16, 2008
    Date of Patent: January 17, 2012
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Han-youl Ryu, Sung-dong Suh, Kyoung-ho Ha, Seong-gu Kim
  • Patent number: 8086114
    Abstract: The present invention discloses filter coefficient changing apparatus and method for use in a dual-polarized optical coherent receiver. The apparatus comprises a controlling unit, a switching unit and a new coefficient obtaining unit. The switching unit is connected between a first filter coefficient updating unit and a first filtering unit and a second filtering unit; the new coefficient obtaining unit generates new filter coefficients for the first filtering unit and the second filtering unit in accordance with filter coefficients outputted by a second filter coefficient updating unit; and the controlling unit generates a control signal that controls switching of the switching unit.
    Type: Grant
    Filed: February 4, 2009
    Date of Patent: December 27, 2011
    Assignee: Fujitsu Limited
    Inventors: Ling Liu, Zhenning Tao, Takahito Tanimura
  • Patent number: 8078065
    Abstract: According to one embodiment, an optical receiver adapted to recover OOK or PAM data carried by a modulated optical carrier has an optical detector adapted to produce a sequence of vector pairs having first and second digital vectors indicative of complex values of first and second polarization components, respectively, of the modulated optical carrier at a corresponding sampling time. The optical receiver also has a digital processor that is connected to receive the sequence and is adapted to perform a rotation on each pair in a manner that tends to compensate for polarization rotation produced by transmitting the modulated optical carrier from an optical transmitter thereof to the optical receiver. The digital processor is further adapted to estimate values of the OOK or PAM data encoded onto each of the first and second polarization components based on the vectors produced by the rotation in a manner responsive to values of energy errors in the estimated values.
    Type: Grant
    Filed: December 19, 2007
    Date of Patent: December 13, 2011
    Assignee: Alcatel Lucent
    Inventor: Ut-Va Koc
  • Patent number: 8055141
    Abstract: An apparatus and method for reducing electrical signal intermodulation by processing a balanced electrical signal in the optical domain in a manner adapted to reduce noise and second order intermodulation, and converting the processed optical signal back to an electrical domain signal with either a single or balanced (differential) outputs.
    Type: Grant
    Filed: December 17, 2007
    Date of Patent: November 8, 2011
    Assignee: Alcatel Lucent
    Inventors: Young-Kai Chen, Andreas Bertold Leven, Mahmoud Rasras, Kun-Yii Tu
  • Patent number: 7965947
    Abstract: An optical system and method includes a source-free optical network unit coupled to an optical fiber for receiving an original carrier signal with downstream data over the optical fiber. The optical network unit includes a modulator configured to remodulate the original carrier signal with upstream data to produce an upstream data signal for transmission back down the optical fiber in a direction opposite to a direction in which that original carrier signal was received.
    Type: Grant
    Filed: October 4, 2007
    Date of Patent: June 21, 2011
    Assignee: NEC Laboratories America, Inc.
    Inventors: Jianjun Yu, Yuanqiu Luo, Ting Wang
  • Patent number: 7894728
    Abstract: A method of compensating phase error between parallel digital signals of a received optical signal, in a coherent optical receiver. A phase differential between the digital signals is determined. A digital skew is imposed between the digital signals, an amount of skew imposed being an integer number of sample periods calculated to most nearly compensate the phase differential. The skewed digital signals are then digitally processed, in the frequency domain, to compensate a residual portion of the phase differential.
    Type: Grant
    Filed: October 17, 2006
    Date of Patent: February 22, 2011
    Assignee: Ciena Corporation
    Inventors: Han Sun, Chandra Bontu, Kim B. Roberts, John Sitch, John Wolczanski
  • Publication number: 20110038642
    Abstract: Technology for detecting an optical data signal carried in a combined optical signal that comprises a carrier optical signal modulated by the optical data signal and also comprises ASE noise. The proposed optical data detector/receiver is provided with an SHG device adapted to generate a second harmonic optical signal of the carrier optical signal modulated by the data signal. In the signal, generated by the SHG, the ASE noise will be essentially reduced.
    Type: Application
    Filed: April 5, 2009
    Publication date: February 17, 2011
    Applicant: ECI TELECOM LTD.
    Inventors: Uri Mahlab, Michael Gutin
  • Patent number: 7873272
    Abstract: An optical pulse monitor (OPM) that determines an optical phase profile for a pulse train by (i) modulating the optical phase of pulses in the pulse train using a periodic waveform and (ii) generating a derivative of a spectrum of the resulting modulated signal with respect to the waveform's amplitude. In one embodiment, an OPM has a phase modulator that modulates the optical phase of pulses in a received pulse train using a periodic waveform supplied by a configurable drive circuit. The drive circuit temporally aligns the waveform with the pulse train to serially produce each of four selected temporal alignments. An optical signal analyzer measures a spectrum of the modulated signal generated by the modulator for each of these four temporal alignments and provides the four measured spectra to a processor. The processor uses the measured spectra to determine two spectrum derivatives with respect to the waveform's amplitude.
    Type: Grant
    Filed: November 13, 2006
    Date of Patent: January 18, 2011
    Assignee: Alcatel-Lucent USA Inc.
    Inventor: Inuk Kang
  • Publication number: 20100329670
    Abstract: A representative optical receiver of the invention receives an optical transverse-mode-multiplexed (TMM) signal through a multimode fiber that supports a plurality of transverse modes. The optical receiver has a plurality of optical detectors operatively coupled to a digital signal processor configured to process the TMM signal to determine its modal composition. Based on the determined modal composition, the optical receiver demodulates each of the independently modulated components of the TMM signal to recover the data encoded onto the TMM signal at the remote transmitter.
    Type: Application
    Filed: June 26, 2009
    Publication date: December 30, 2010
    Inventors: Rene-Jean Essiambre, Roland Ryf, Peter J. Winzer
  • Patent number: 7840144
    Abstract: An optical transceiver is provided for optical communications with additive noise compensation. The system and method are disclosed for the additive noise cancellation, which is typically a vibration noise, caused by moving platform, where the transceiver is located. The transceiver comprises an additive noise sensor and a digital signal processing (DSP) unit which implements variable step size technique to adjust the filter weight in the least square estimate of the noise signal. In the preferred embodiment the digital signal processing is applied both at the transmission and the receiving side. The optical device is packed for ground-satellite and inter-satellite communications applications with resistance to high-energy X-rays, gamma rays and cosmic rays. The optical device sustains its operation characteristics under launch load.
    Type: Grant
    Filed: October 4, 2007
    Date of Patent: November 23, 2010
    Assignee: CeLight, Inc.
    Inventors: Isaac Shpantzer, Sabera Kazi
  • Publication number: 20100232811
    Abstract: An apparatus is disclosed for the optical generation of clock signals with tunable frequency and low jitter. A laser source serves as both the carrier used to transmit the clock signal for use by other optical, electronic or hybrid circuit elements and the original modulation time base. A fraction of the original laser source undergoes one or more stages of frequency division before being recombined as a modulation signal with the remaining laser beam. Transmission of the resulting signal via single mode fiber and dividers retains the low jitter properties of the modulated signal. By starting with a clock signal of optical frequency then dividing downward in frequency, comparatively high frequency clocks may be generated, notably in the GigaHertz and TeraHertz frequency ranges.
    Type: Application
    Filed: September 22, 2008
    Publication date: September 16, 2010
    Applicant: FTL Systems, Inc.
    Inventors: John C. Willis, Ruth A. Betcher
  • Patent number: 7792436
    Abstract: A small size and low cost optical receiving apparatus, which can stably demodulate the signal, lights in accordance with the differential M-phase shift keying (DMPSK) system. An optical receiving apparatus comprises a light branching unit for branching the differential M-phase shift keying signal beam into four signal light beams, a delay adjusting unit giving a delay time difference of one symbol between a first signal light beam and a second signal light beam and between a third signal light beam and a fourth signal light beam, a demodulating unit for outputting a least two demodulated light signals through respective interferences between the first signal light beam and the second signal light beam, and between the third signal light beam and the fourth signal light beam on one plane which is not parallel to any signal light beam, and at least two optical detectors for converting at least two light signals into electrical signals.
    Type: Grant
    Filed: March 29, 2006
    Date of Patent: September 7, 2010
    Assignee: Fujitsu Limited
    Inventors: Takeshi Hoshida, Nobuhiro Fukushima
  • Patent number: 7787773
    Abstract: It is provided a radio oscillating system for oscillating a radio signal. The system has an optical modulator for oscillation, a modulating means for inputting a modulating signal of a frequency of fm into the optical modulator to modulate a carrier wave so as to interpose sideband waves onto the carrier wave at positions shifted with respect to the frequency of the carrier wave by the frequency “fm”; and an optical receiver for oscillation for receiving beam from the optical modulator and converting the beam into an electrical signal. The system further has a radiating means for radiating radio signal of a frequency of 2fm based on the electrical signal. An input voltage Vp-p applied on the optical modulator is 1.0 times or more and 1.99 times or less of a half-wavelength voltage V? of the optical modulator.
    Type: Grant
    Filed: September 14, 2006
    Date of Patent: August 31, 2010
    Assignee: NGK Insulators, Ltd.
    Inventors: Jungo Kondo, Osamu Mitomi, Kenji Aoki, Yuichi Iwata, Tetsuya Ejiri
  • Patent number: 7734193
    Abstract: An apparatus and method for detecting an output power level of an optical receiver, in order to hold output signal levels constant over changing input optical levels. A photodetector detects an optical signal, and a current from the photodetector is applied an amplifier. The amplifier may be either a differential trans-impedance amplifier, or a dual trans-impedance amplifier coupled to a differential output amplifier. An output of the amplifier is applied o a signal detector, wherein an output signal of the signal detector is an indication of an output power level of the optical receiver.
    Type: Grant
    Filed: August 10, 2005
    Date of Patent: June 8, 2010
    Assignee: Tri Quint Semiconductor, Inc.
    Inventor: Chris J. Day
  • Patent number: 7733562
    Abstract: A method of optically equalizing a multi-level (amplitude or phase) optical signal through the effect of an optical equalizer wherein the optical equalizer (OEQ) is placed at either a transmission end or a receiver end of the optical communications link and a tap delay characteristic of the OEQ need not be determined by symbol spacing, rather it may advantageously be adjusted to desirably compensate non-linear mapping performed in the modulation process or simultaneous operation on a plurality of wavelength division multiplexed (WDM) channels.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: June 8, 2010
    Assignee: Alcatel-Lucent USA Inc.
    Inventors: Christopher Doerr, Alan Gnauck, Gregory Raybon, Peter Winzer
  • Patent number: 7684712
    Abstract: A method of recovering a most likely value of each symbol transmitted through an optical communications network using a high speed optical signal. A stream of multi-bit digital samples of the optical signal is processed to generate a respective multi-bit estimate X?(n) of each transmitted symbol. A first function is applied to each symbol estimate X?(n) to generate a corresponding soft decision value {tilde over (X)}(n). Each soft decision value {tilde over (X)}(n) is processed to generate a corresponding hard decision value. {circumflex over (X)}(n) having an ideal amplitude and phase. A plurality of successive soft decision values and hard decision values are processed to determine a second function, which is applied to each soft decision value {tilde over (X)}(n) to generate a most likely symbol value {circumflex over ({circumflex over (X)}(n).
    Type: Grant
    Filed: October 20, 2006
    Date of Patent: March 23, 2010
    Assignee: Nortel Networks Limited
    Inventors: Kim B. Roberts, Chandra Bontu, Kuang Tsan Wu, Han Sun
  • Patent number: 7596326
    Abstract: An optical receiver having a photodetector coupled to an external optical fiber for receiving an optical communications signal and converting it into an electrical signal; an RF amplifier coupled to the electrical output of the photodetector and generating an output signal with distortion; and a post-distortion circuit connected to the output of the RF amplifier for canceling the distortion in the output signal produced by the RF amplifier.
    Type: Grant
    Filed: October 27, 2005
    Date of Patent: September 29, 2009
    Assignee: Emcore Corporation
    Inventors: Eva Peral, Bryon L. Kasper
  • Patent number: 7474860
    Abstract: In an over-sampled maximum-likelihood sequence estimation (MLSE) receiver system, the optimal sample spacing is determined for a variety of conditions. In an illustrative implementation, the system includes an optical filter for tightly filtering an incoming optical data signal with an on-off-keying (OOK) non-return-to-zero (NRZ) format, followed by an optical-to-electrical converter, an electrical filter, a sampler, and a MLSE receiver. The sampler samples the filtered electrical data signal twice each bit period with unequal sample spacings. For wide optical filtering bandwidths, the optimal sample spacing occurs at less than 50% of a bit period. For narrow bandwidths, the optimal sample instances occur closer to the maximum eye opening.
    Type: Grant
    Filed: December 19, 2005
    Date of Patent: January 6, 2009
    Assignee: Alcatel-Lucent USA Inc.
    Inventors: Rene Jean Essiambre, Michael Rubsamen, Peter J. Winzer
  • Patent number: 7460792
    Abstract: In an optical communication-use receiving circuit of the present invention, the pulse width of the received pulse which is a binary signal corresponding to the signal optical pulse is specified by using an integration circuit and a trigger generating circuit. If the pulse width of the received pulse is not shorter than a predetermined value, a signal having a fixed pulse width is outputted as an output signal from a one-shot pulse generating circuit, so that a pulse having a constant pulse width corresponding to the specified communication speed is outputted. Accordingly, if the pulse width deriving from the signal optical pulse is larger than a certain value, the communication is deemed as a low-speed communication, and a pulse having a constant pulse width corresponding to the communication speed is outputted. As a result, it is possible to realize a small-size receiving circuit and a small-size electronic device which require no external switching-over terminal.
    Type: Grant
    Filed: July 7, 2005
    Date of Patent: December 2, 2008
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Naruichi Yokogawa, Takeshi Nishino
  • Patent number: 7421212
    Abstract: Detecting a pulse of a signal includes receiving the signal and a light beam. The signal drives a spatial light modulator to modulate the light beam, where the complex amplitude of the modulated light beam is proportional to the signal current. The modulated light beam passes through an optical system and is detected by an optical detector array. A processor identifies a portion of the signal comprising the pulse.
    Type: Grant
    Filed: November 19, 2004
    Date of Patent: September 2, 2008
    Assignee: Raytheon Company
    Inventor: John B. Allen
  • Patent number: 7418212
    Abstract: A system and method for detecting digital symbols carried in a received optical signal. The system comprises a functional element operative to receive a stream of samples of an electrical signal derived from the received optical signal and to evaluate a non-linear function of each received sample, thereby to produce a stream of processed samples. The system also comprises a detector operative to render decisions about individual symbols present in the received optical signal on the basis of the stream of processed samples. In an embodiment, the non-linear function computes substantially the square root of each received sample.
    Type: Grant
    Filed: October 1, 2003
    Date of Patent: August 26, 2008
    Assignee: Nortel Networks Limited
    Inventor: Chandra Bontu
  • Patent number: 7411726
    Abstract: An optical, multi-channel, Differential Phase Shift Keying (DPSK) receiver demodulates multiple Wavelength Division Multiplexed (WDM) channels using at least one interferometer. This distributes expense of the interferometer(s) over all channels of an optical signal, allowing for deployment of cost-effective, scalable, wideband, WDM DPSK systems. For example, for an 80 channel WDM link, the receiver uses a single interferometer instead of eighty interferometers and associated stabilization hardware, dramatically reducing size, weight, power, and cost. The receiver is architecturally compatible with existing interferometer technologies so previous development and qualification efforts can be leveraged. This allows for expedited technology insertion into existing optical communications networks, including terrestrial and space-based optical networks.
    Type: Grant
    Filed: March 8, 2007
    Date of Patent: August 12, 2008
    Assignee: Massachusetts Institute of Technology
    Inventor: David O. Caplan
  • Patent number: 7376359
    Abstract: The invention discloses a digital adjusting method for an optical receiver module, and the method implements real-time monitor of parameters, on-line adjustment and non-linear compensation. The digital optical receiver module includes elements as follow: a voltage output circuit of optical power detection 24, a DC/DC voltage boost circuit 22 and a bias voltage adjusting unit which is consisted of an optical-electronic conversion circuit 21; a digital adjusting unit 25, an analog-digital converter (A/D converter) 26 and a memory 27. The digital adjusting unit 25 makes on-line adjustment and implements temperature compensation and dark current compensation of the optical receiver module. The A/D converter 26 monitors the optical power, the working temperature and the bias voltage of the optical detector in real time. The memory 27 stores parameters of the optical receiver module for comparison with a detected optical power and measured temperature etc. and for on-line interrogation.
    Type: Grant
    Filed: March 5, 2003
    Date of Patent: May 20, 2008
    Assignee: Huawei Technologies Co., Ltd.
    Inventor: Zhenyu Tang