Including Polarization Patents (Class 398/205)
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Patent number: 8086114Abstract: 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: GrantFiled: February 4, 2009Date of Patent: December 27, 2011Assignee: Fujitsu LimitedInventors: Ling Liu, Zhenning Tao, Takahito Tanimura
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Patent number: 8086113Abstract: An optical mixing part mixing a received optical signal and local oscillator light in at least two kinds of phases and extracting at least two-system optical signals corresponding to each light phase; a photoelectric conversion part converting the at least two-system optical signals obtained in the optical mixing part into electric analog signals; an analog-to-digital conversion part converting the electric analog signals into digital signals; and a control part processing the digital signals thereby detecting a light phase difference between the respective systems in the optical mixing part and supplying a signal for correcting the light phase between the systems to the optical mixing part to control the optical mixing part so that the light phase difference becomes to zero or close to a desired value when the light phase difference has a shift from the desired value.Type: GrantFiled: April 16, 2008Date of Patent: December 27, 2011Assignee: Fujitsu LimitedInventors: Hisao Nakashima, Takeshi Hoshida, Takahito Tanimura
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Patent number: 8081884Abstract: In a fixed delay optical communication system, rate adjustable differential phase shift key (DPSK) techniques eliminate the need for multiple comparing modules, each corresponding to a different data rate. Setting alternative data rates at integer multiples of the fundamental data rate of the optical communication system allows the system to process the respective integer number of symbols per period of the system, wherein the period of the system is the inverse of the fundamental data rate. Pulse carving techniques may be used to set the duty cycle of clock levels associated with a clock signal. The clock levels may be combined with respective symbols to provide optical symbols having a duty cycle less than 100%.Type: GrantFiled: September 10, 2010Date of Patent: December 20, 2011Assignee: The MITRE CorporationInventors: David R. Gervais, Jeffrey R. Minch, Daniel J. Townsend
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Patent number: 8078065Abstract: 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: GrantFiled: December 19, 2007Date of Patent: December 13, 2011Assignee: Alcatel LucentInventor: Ut-Va Koc
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Patent number: 8073345Abstract: A method for determining symbols PSK modulated on an optical carrier includes interfering a first polarization component of the modulated optical carrier and a reference optical carrier in a first optical mixer and interfering the first polarization component of the modulated optical carrier and the reference with a different relative phase in a second optical mixer. The method also includes sampling the interfered carriers from the first optical mixer to produce first digital sampled values and sampling the interfered carriers from the second optical mixer to produce second digital sampled values. The first and second digital sampled values of a sampling period form a first complex sampling value thereof. The method also includes offsetting a phase of a complex signal value corresponding to each first complex sampling value to correct for a phase error caused by a frequency offset between the modulated and reference optical carriers.Type: GrantFiled: December 22, 2006Date of Patent: December 6, 2011Assignee: Alcatel LucentInventors: Young-Kai Chen, Noriaki Kaneda, Ut-Va Koc, Andreas Bertold Leven
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Patent number: 8068742Abstract: A high-speed optical transmitter comprises multiple digital lanes that are provided to a bank of digital-to-analog converters. The analog signals are then used to Phase Shift Keyed (PSK) modulation using a Chirp Managed Laser (CML)-based transmitter, and potentially using dual polarization. A corresponding optical receiver receives the sequence of optical signals at a demodulator. For each polarization, the demodulator includes a corresponding demodulation channel that is configured to demodulate that polarization component of the optical signal into one or more signal components. Each of these signal components is converted into a corresponding digital signal using a corresponding analog-to-digital converter. In the case of higher-order PSK modulation (e.g., 8PSK or higher), for each polarization, the analog converter has a lower sampling rate than for QPSK modulation.Type: GrantFiled: July 10, 2008Date of Patent: November 29, 2011Assignee: Finisar CorporationInventors: Christopher R. Cole, Daniel Mahgerefteh, The'Linh Nguyen, Andrew C. Singer, Naresh Ramnath Shanbhag
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Patent number: 8064544Abstract: In the field of communication and transmission, a method and a device for receiving an OPFDM-DQPSK signal are provided. The device includes a power splitter, adapted to split the OPFDM-DQPSK signal into two beams of signals; a polarization beam splitter (PBS), adapted to splitting one of the two beams of signals into a first signal and a second signal; a demultiplexer (Demux), adapted to demultiplex the other beam of signal to obtain a third signal and a fourth signal; two delayers, adapted to delay the third signal and the fourth signal respectively; a first frequency-mixing receiving module, adapted to perform frequency-mixing receiving on the first signal and the delayed third signal; a second frequency-mixing receiving module, adapted to perform frequency-mixing receiving on the second signal and the delayed fourth signal; and a decision recovery module, adapted to recover four logical sequences by performing decision on the four electrical signals.Type: GrantFiled: November 6, 2009Date of Patent: November 22, 2011Assignee: Huawei Technologies Co., Ltd.Inventors: Liangchuan Li, Chan Zhao, Lun Wei
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Patent number: 8064767Abstract: The present invention provides a system and method of optical communications that utilize coherent detection technique and optical orthogonal frequency division multiplexing for phase encoded data transmission. In particular the invention addresses a device and method for digital polarization compensation of optical signals with up to 100 Gb/s transmission rate received via an optical link. The polarization compensation operates in two modes: acquisition mode and tracking mode. The polarization recovery is performed at the receiver side using the received digital signal conversion into frequency domain and separate reconstruction of the polarization state in each spectral component.Type: GrantFiled: March 11, 2008Date of Patent: November 22, 2011Assignee: CeLight, Inc.Inventors: Isaac Shpantzer, Alexander Genusov, Yehouda Meiman, Jacob Khurgin
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Patent number: 8041233Abstract: An embodiment of the invention is a technique to equalize received samples. A coefficient generator generates filter coefficients using a rotated error vector. A filter stage generates equalized samples or slicer input vector from received samples or rotated received samples using the filter coefficients. The received samples are provided by a receiver front end in an optical transmission channel carrying transmitted symbols.Type: GrantFiled: July 14, 2004Date of Patent: October 18, 2011Assignee: Fundación TarpuyInventors: Mario Rafael Hueda, Diego Ernesto Crivelli, Hugo Santiago Carrer
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Publication number: 20110243575Abstract: The present application discloses a method for adaptive blind equalization of a PSK signal, an equalizer and a receiver. According to embodiments as provided, a conjugate product of a current output and a precedent output of an FIR filter is calculated, an equalization coefficient is updated using the conjugate product, and then an input signal is filtered using the FIR filter with the updated equalization coefficient. The embodiments as provided is applicable to adaptive blind equalization of any phase shift keying signal including a BPSK signal.Type: ApplicationFiled: October 18, 2010Publication date: October 6, 2011Applicant: Fujitsu LimitedInventors: Meng YAN, Huijian Zhang, Zhenning Tao, Shoichiro Oda
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Patent number: 8023834Abstract: A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver.Type: GrantFiled: May 13, 2010Date of Patent: September 20, 2011Assignee: Alcatel LucentInventor: Ut-Va Koc
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Patent number: 8014685Abstract: A coherent optical receiver of the invention combines local oscillator light having orthogonal polarization components in which the optical frequencies are different to each other, and received signal light, in an optical hybrid circuit, and then photoelectrically converts this in two differential photodetectors. Then this is converted to a digital signal in an AD conversion circuit, and computation processing is executed in a digital computing circuit using the digital signal, to estimate received data. At this time, the optical frequency difference between the orthogonal polarization components of the local oscillator light is set so as to be smaller than two times the signal light band width, and larger than a spectrum line width of the signal light source and the local oscillator light source. As a result, it is possible to realize a small size polarization independent coherent optical receiver that is capable of receiving high speed signal light.Type: GrantFiled: September 27, 2007Date of Patent: September 6, 2011Assignee: Fujitsu LimitedInventor: Takeshi Hoshida
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Patent number: 8014686Abstract: An optical receiver utilizes differential quadrature phase-shift keying (DQPSK) demodulation and electrical crosstalk rejection to relax requirements on filter misalignment with a carrier signal and to enable electronic polarization demultiplexing of optical signals. The optical receiver uses additional polarization state information when performing differential phase measurements on the optical signals. This provides information that ensures that data can be recovered by the optical receiver regardless of the state of polarization introduced during transmission of the optical signals. The optical receiver over samples the optical signals, which enables electrical polarization demultiplexing of the optical signals. The electrical crosstalk rejection provides a tracking algorithm that isolates received optical signals, and reduces crosstalk between data sequences.Type: GrantFiled: March 20, 2008Date of Patent: September 6, 2011Assignee: Infinera CorporationInventors: Jeffrey Thomas Rahn, Wei Chen
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Patent number: 8005368Abstract: A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments.Type: GrantFiled: December 5, 2007Date of Patent: August 23, 2011Assignee: Ciena CorporationInventors: Kim Roberts, Han Sun
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Patent number: 7995929Abstract: An optical data receiver comprises an optical input for receiving optical data signals, an optical sputter for splitting the optical signals into first and second receiver arms, an optical filter in the first receiver arm, means for increasing an intensity ratio of optical signal strength in the first receiver arm to optical signal strength in the second receiver arm, means for adjusting a phase difference between the first and second receiver arms, and an optical coupler for coupling outputs of the first and second receiver arms to a photodetector. The receiver of the present invention selectively filters a carrier component of received optical data signals, adjusts the relative strength of the carrier component and the received signal and then recombines them. In this way efficient optical transmission can be achieved with direct detection at the receiver, without the need for a complex receiver design including a local oscillator.Type: GrantFiled: August 9, 2005Date of Patent: August 9, 2011Assignee: Xtera Communications Ltd.Inventors: Stephen Michael Webb, Stephen Desbrulais
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Patent number: 7991301Abstract: An optical apparatus comprising: a branching unit branching an input light modulated by DQSPK format and thereby outputting a first branched light and a second branched light; a first branch and a second branch inputting the first branched light and the second branched light, respectively, the first branch and the second branch having an interferometer, a photo detector, and discriminator and demodulating I-signal and Q-signal, respectively; and an abnormality detection unit detecting an abnormality of the input light based on a synchronized detection of a first demodulated signal output from the photo detector in the first branch and a first recovered signal output from the discriminator in the first branch, and a synchronized detection of a second demodulated signal output from the photo detector in the second branch and a second recovered signal output from the discriminator in the second branch.Type: GrantFiled: March 28, 2008Date of Patent: August 2, 2011Assignee: Fujitsu LimitedInventors: Noriaki Mizuguchi, Takashi Toyomaki, Yoshikazu Terayama, Kenichi Kaburagi
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Patent number: 7965946Abstract: A system and method are provided for calibrating skew in a multichannel optical transport network (OTN) transmission device. The method accepts a pair of 2n-phase shift keying (2nPSK) modulated signals via Ix and Qx electrical signal paths, where n>1. Likewise, a pair of 2p-PSK modulated signals are accepted via Iy and Qy electrical signal paths where p>1. The Ix, Qx, Iy, and Qy signals are correlated to a preamble/header portion of an OTN frame. A voltage on the Ix signal path is compared with Qx, and VO12 voltage is generated. A voltage on the Iy signal path is compared with Qy, and VO34 is generated. One of the Ix or Qx voltages is compared with one of Iy or Qy voltages to generate VOxy. Then, the VO voltages are minimized in response to adjusting time delay modules in the Ix, Qx, Iy, and Qy signals paths.Type: GrantFiled: July 8, 2008Date of Patent: June 21, 2011Assignee: Applied Micro Circuits CorporationInventors: Keith Conroy, Omer Acikel, Francesco Caggioni
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Patent number: 7962048Abstract: The present invention is a method and apparatus to make an estimate of the phase of a signal relative to the local oscillator in an optical coherent detection subsystem that employs a digital signal processor having a parallel architecture. The phase estimation method comprises operations that do not use feedback of recent results. The method includes a cycle count function so that the phase estimate leads to few cycle slips. The phase estimate of the present invention is approximately the same as the optimal phase estimate.Type: GrantFiled: October 1, 2009Date of Patent: June 14, 2011Inventor: Michael George Taylor
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Patent number: 7957654Abstract: A coherent optical receiver of the invention combines local oscillator light having orthogonal polarization components in which the optical frequencies are different to each other, and received signal light, in an optical hybrid circuit, and then photoelectrically converts this in two differential photodetectors. Then this is converted to a digital signal in an AD conversion circuit, and computation processing is executed in a digital computing circuit using the digital signal, to estimate received data. At this time, the optical frequency difference between the orthogonal polarization components of the local oscillator light is set so as to be smaller than two times the signal light band width, and larger than a spectrum line width of the signal light source and the local oscillator light source. As a result, it is possible to realize a small size polarization independent coherent optical receiver that is capable of receiving high speed signal light.Type: GrantFiled: September 27, 2007Date of Patent: June 7, 2011Assignee: Fujitsu LimitedInventor: Takeshi Hoshida
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Patent number: 7936999Abstract: In a coherent optical receiver, a method of at least partially compensating Polarization Dependent Loss (PDL) of an optical signal received through an optical communications system. A respective multi-bit sample stream of each one of a pair of orthogonal received polarizations of the optical signal is tapped, and used to derive a respective metric value indicative of a quality of each multi-bit sample stream. A gain of an analog front end of the coherent optical receiver is adjusted based on the derived metric values.Type: GrantFiled: September 20, 2006Date of Patent: May 3, 2011Assignee: Ciena CorporationInventors: Mark Hawryluck, Kim B. Roberts, Kuang Tsan Wu
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Publication number: 20110033195Abstract: 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: ApplicationFiled: August 6, 2009Publication date: February 10, 2011Inventor: MICHAEL Y. FRANKEL
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Patent number: 7884996Abstract: A delay-line demodulator for demodulating a differential quadrature phase shift keying (DQPSK) signal is provided. The demodulator includes two Mach-Zehnder interferometers individually comprising two waveguides having different lengths therebetween and through which a light signal branched from the DQPSK signal propagates, respectively. A phase of the light signal propagating at one of the waveguides is delayed as compared to a phase of the light signal propagating at another one of the waveguides, wherein a divergence amount of polarization is adjusted by driving sets of heaters that are facing each other and sandwiching a half wavelength plate therebetween.Type: GrantFiled: December 2, 2009Date of Patent: February 8, 2011Assignee: Furukawa Electric Co., Ltd.Inventors: Junichi Hasegawa, Kazutaka Nara
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Patent number: 7865080Abstract: In order to reduce mutual interferences between POLMUX and signals, the signals are transmitted with differed to each other carrying signals, thereby making it possible to obtain the circular polarization of each resulting POLMUX signal. Each second POLMUX signal is transmissible with an opposite circular polarization. In order to reduce also interferences when only one modulated data signal is transmitted through a POLMUX channel, a polarization plane of modulated data signals of each second POLMUX channel is turned at 45°. In a variant, polarization multiplex signals are produces and the resulting polarizations thereof in adjacent channels are perpendicular to each other.Type: GrantFiled: January 25, 2006Date of Patent: January 4, 2011Assignee: Nokia Siemens Networks GmbH & Co. KGInventors: Nancy Hecker, Werner Paetsch, Dirk van den Borne
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Patent number: 7860394Abstract: In an optical receiver according to the present invention, an input signal light subjected to the differential quadrature phase shift keying (DQPSK) is incident on a PANDA type fiber in a linearly polarized state by 45°, so that a delay time difference corresponding to one symbol is generated between orthogonal polarization components in the DQPSK signal light, and then, the signal light is branched by a half mirror into two, to be sent to first and second paths respectively, thereby giving, by a ¼ wave plate disposed on one of the paths, a relative birefringent amount difference of ?/2 between the lights propagated through the respective paths. Then, each of the lights propagated through the first and second paths is separated into two orthogonal polarization components by a polarization beam splitter, and the respective polarization components are received by a differential reception circuit so that in-phase components and quadrature components in the DQPSK signal are demodulated.Type: GrantFiled: March 19, 2009Date of Patent: December 28, 2010Assignee: Fujitsu LimitedInventor: Takeshi Hoshida
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Patent number: 7860406Abstract: A self-polarization diversity technique to combat PMD in a direct-detection optical OFDM system. This technique does not require any dynamic polarization control, and can simultaneous compensate PMD in a WDM system with one device. Simulation results show that this technique virtually completely eliminates the PMD impairments in direct-detection optical OFDM systems.Type: GrantFiled: September 14, 2007Date of Patent: December 28, 2010Assignee: Alcatel-Lucent USA Inc.Inventor: Chongjin Xie
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Publication number: 20100316393Abstract: An apparatus and method are provided for receiving an optical signal having an optical carrier component and at least one information-bearing optical sideband. In general, an optical filter arrangement (110) is used to separate the optical carrier component from the information-bearing optical sideband. First and second optical splitters (126, 128) divide the optical power in the optical carrier and the optical sideband, respectively, into corresponding sub-components. The sub-components of the optical carrier have substantially orthogonal polarisation states, which is an optional characteristic of the sideband sub-components. First and second optical coupling devices (142, 144) respectively each combine one of the optical carrier sub-components with a corresponding one of the optical sideband sub-components. Optical detectors (158, 160) detect the outputs of the combiners (142, 144).Type: ApplicationFiled: February 20, 2009Publication date: December 16, 2010Applicant: Ofidium Pty. Ltd.Inventors: Brendon James Schmidt, Arthur Jame Lowery, Jean Armstrong
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Patent number: 7826752Abstract: Apparatuses, systems, and methods are disclosed that provide for an agile coherent optical modem that can generate agile RF waveforms and data rates on a generic opto-electronic hardware platform. An “agile coherent optical modem” [ACOM] approach to optical communications by employing a software configurable and adaptive technologies to the transport system. The ACOM generate agile RF waveforms and data rates on a generic opto-electronic hardware platform. By employing advanced communication techniques to the optical domain such as wavelength agility, waveform agility, and symbol rate agility, it is possible to enable robust optical communications. The ACOM allows for the transport capacity of a communications link to be varied, thereby accommodating variations in transport conditions, range, opacity, etc.Type: GrantFiled: June 2, 2006Date of Patent: November 2, 2010Assignee: Level 3 Communications, LLCInventors: Raymond Zanoni, David J. Copeland, Alistair J. Price
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Patent number: 7822350Abstract: Digital compensation of the polarization-mode dispersion (PMD) effects experienced by an optical signal in a transmission link is achieved. A digital representation of the optical fields of two orthogonal polarization components of an optical signal, defined by a polarization beam splitter (PBS), is first obtained. The fiber transmission link is treated as a concatenation of multiple virtual PMD segments, each having two specific principle-state-of-polarization (PSP) axes and causing a differential group-delay (DGD) and a phase delay between two signal components that are polarized along the two PSP axes. The best guesses of the parameters of the PMD segments and the relative orientation between the PSP axes of the last PMD segment and the characteristic polarization axes of the PBS are dynamically obtained. The digital representation of at least one generic component of the field of the optical signal is then computed through matrix operations by using the best guesses.Type: GrantFiled: May 9, 2008Date of Patent: October 26, 2010Assignee: Alcatel-Lucent USA Inc.Inventor: Xiang Liu
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Patent number: 7809284Abstract: An apparatus, a polarization diversity receiver and a method of receiving a received optical signal. In one embodiment, the apparatus includes: (1) an optical device configured to separate in-phase and quadrature components of a received optical signal, to transmit the in-phase components to a first optical output thereof and to transmit the quadrature components to a second optical output thereof, (2) a first polarization splitter coupled to receive light at the first optical output and (3) a second polarization splitter coupled to receive light at the second optical output.Type: GrantFiled: June 23, 2006Date of Patent: October 5, 2010Assignee: Alcatel-Lucent USA Inc.Inventors: Noriaki Kaneda, Andreas B. Leven
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Publication number: 20100221020Abstract: A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver.Type: ApplicationFiled: May 13, 2010Publication date: September 2, 2010Inventor: Ut-Va Koc
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Patent number: 7769305Abstract: In a coherent optical receiver, a frequency domain engine digitally processes at least two multi-bit sample streams of a received optical signal. The frequency domain engine includes a Fast Fourier Transform (FFT) filter for computing a complex vector representative of a frequency-domain spectrum of the received optical signal. A transpose and add block computes a vector sum of the complex vector and a transposed version of the complex vector, and an Inverse Fast Fourier Transform (IFFT) filter computes a complex output vector from the addition result. With this arrangement, parallel real filter operations are efficiently performed on each of the multi-bit sample streams, using a single back-to-back FFT-IFFT filter structure.Type: GrantFiled: September 21, 2006Date of Patent: August 3, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Han Sun, Chandra Bontu, Kuang Tsan Wu
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Patent number: 7747169Abstract: A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver.Type: GrantFiled: December 22, 2006Date of Patent: June 29, 2010Assignee: Alcatel-Lucent USA Inc.Inventor: Ut-Va Koc
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Patent number: 7711273Abstract: In one embodiment, a receiver of the invention has an optical detector coupled to a digital processor. The optical detector is adapted to mix the received optical quadrature-amplitude modulation (QAM) signal with an optical local oscillator (LO) signal having a time-varying phase offset with respect to the carrier frequency of the QAM signal to produce two digital measures of the QAM signal. The digital processor is adapted to: (i) determine the amplitude and phase differentials for each QAM-symbol transition based on these digital measures; (ii) adjust each phase differential for an amount of phase drift associated with the time-varying phase offset; (iii) map each QAM-symbol transition onto a constellation point of a 2D decision map using the transition's amplitude differential and adjusted phase differential; and (iv) based on the mapping results, recover the data encoded in the optical QAM signal.Type: GrantFiled: March 3, 2006Date of Patent: May 4, 2010Assignee: Alcatel-Lucent USA Inc.Inventor: Ut-Va Koc
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Publication number: 20100092176Abstract: To provide a polarization-diverse, heterodyne optical receiving system, a light signal is transmitted into an optical fiber having a plurality of optical sensors that are distinguishable using a multiplexing arrangement. A return light signal from the optical fiber is mixed with an optical local oscillator light signal, where the mixing outputs plural output signal portions having different polarizations. A birefringence of a particular optical sensor is determined based on the plural signal portions.Type: ApplicationFiled: October 14, 2009Publication date: April 15, 2010Applicant: SCHLUMBERGER TECHNOLOGY CORPORATIONInventors: Arthur H. Hartog, Dominic Brady, Maxwell R. Hadley
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Patent number: 7684713Abstract: A calculation processing unit controls temperature of a Peltier device based on a slope of a waveform obtained by subtracting a waveform of a B-arm monitoring signal from a waveform of an A-arm monitoring signal and a value obtained by subtracting a value B of the B-arm monitoring signal from a value A of the A-arm monitoring signal. Similarly, the calculation processing unit controls a phase of the A-arm and a phase of the B-arm. An A-arm side micro-controller controls temperature of an A-arm side heater 22 based on the value of the A-arm monitoring signal, and controls the phase of the A-arm. A B-arm side micro-controller controls temperature of a B-arm side heater based on the value B of the B-arm monitoring signal, and controls the phase of the B-arm.Type: GrantFiled: November 7, 2006Date of Patent: March 23, 2010Assignee: Fujitsu LimitedInventors: Yoshikazu Terayama, Noriaki Mizuguchi, Eiji Ishikawa, Takashi Toyomaki, Kenichi Kaburagi, Takeshi Hoshida, Jens Rasmussen, Akihiko Isomura
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Patent number: 7668468Abstract: The present invention relates to a numerous user laser communications optical system. Numerous optical signals comprising a number of channels are simultaneously received and demultiplexed (and/or multiplexed and transmitted) at a numerous access communication device. The numerous access communication device may comprise multiple stages that each include a multiple order waveplate and a polarizing beam splitter. The multiple order waveplate is configured so that it retards a first electrical field component of signals corresponding to certain channels in a frequency grid in an integer multiple of wavelengths with respect to a second electrical field component, and retards a first electrical field component of signals corresponding to other channels in the frequency grid in an integer multiple of wavelengths plus one-half a wavelength with respect to a second electrical field component. Separation can then be performed on the basis of the resulting opposite polarization.Type: GrantFiled: September 28, 2005Date of Patent: February 23, 2010Assignee: Ball Aerospace & Technologies Corp.Inventors: Isabella T. Lewis, Robert W. Kaliski
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Patent number: 7660533Abstract: A method of data compression and transmission include splitting a wave function representative of an input data set into an arbitrarily oriented elliptical polarization state and a comparator wave function state, the comparator wave function state being transmitted to a detector. A quantum Fourier transform is performed on the arbitrarily oriented elliptical polarization state to yield a quantum computational product. A quantum Hadamard transform is performed on the quantum computational product to yield one of two possible quantum particle outputs. The input data set is reconstructed based upon the coincident arrival of the comparator wave function state and one of the two quantum particle outputs. A method is performed on either a quantum computer or a digital computer. An optical bench with appropriate electronics is particularly well suited to function as a quantum computer for the compression and transmission of data corresponding to sound.Type: GrantFiled: August 4, 2005Date of Patent: February 9, 2010Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Ronald E. Meyers, Keith S. Deacon
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Publication number: 20100014873Abstract: The invention relates to optical communication, in particular to compensation of non-linear distortions incurred in high bit-rate optical communication systems. A method and system for compensating self-phase modulation at an optical receiver of an optical transmission system using polarization division multiplexing and a modulation scheme with constant amplitude is proposed. The method comprises the step of performing a phase modulation on a received signal, wherein the received signal comprises two signal components associated with two orthogonal polarizations, each component comprising an in-phase sub-component and a quadrature-phase sub-component, thereby spanning a four-dimensional space. The phase modulation is determined by evaluating an error signal which depends on the distance in the four-dimensional space between the received signal after the phase modulation and a four-dimensional sphere defined by target constellation points of the optical transmission system.Type: ApplicationFiled: July 2, 2009Publication date: January 21, 2010Inventor: Henning Bulow
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Patent number: 7649678Abstract: A delay-line demodulator for demodulating a differential quadrature phase shift keying (DQPSK) signal is provided. The demodulator includes two Mach-Zehnder interferometers individually comprising two waveguides having different lengths therebetween and through which a light signal branched from the DQPSK signal propagates, respectively. A phase of the light signal propagating at one of the waveguides is delayed as compared to a phase of the light signal propagating at another one of the waveguides, wherein a divergence amount of polarization is adjusted by driving sets of heaters that are facing each other and sandwiching a half wavelength plate therebetween.Type: GrantFiled: October 9, 2008Date of Patent: January 19, 2010Assignee: Furukawa Electric Co., Ltd.Inventors: Junichi Hasegawa, Kazutaka Nara
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Patent number: 7620326Abstract: The invention relates to a method for transmitting at least one first and second data signal in polarization multiplex. To this end, the invention provides that, in a first step, the first data signal is, on the transmit side, modulated to a sideband of a first carrier signal for generating a first sideband-modulated signal, and the second data signal is modulated to a sideband of a second carrier signal in order to generate a second sideband-modulated signal. In a second step, the first and second sideband-modulated signal are subsequently polarized orthogonal to one another, combined to form an optical multiplex signal and transmitted. In a third step, the optical multiplex signal is, on the receive side, guided via a polarization control element to a polarization splitter that separates the transmitted optical multiplex signal into the first and second sideband-modulated signal.Type: GrantFiled: July 7, 2003Date of Patent: November 17, 2009Assignee: Nokia Siemens Networks GmbH & Co KGInventor: Christoph Glingener
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Patent number: 7613403Abstract: A first optical splitter splits an input optical signal and outputs it to first and second optical paths. A second optical splitter outputs the optical signal from the first optical path to third and fourth optical paths. A third optical splitter outputs the optical signal from the second optical path to fifth and sixth optical paths. In the second optical path, 1-symbol delay element and ?/4 phase shifter element are configured. In the fourth optical path, ?/2 phase shifter element is configured. First and second adjuster circuits adjust the optical path length of the second and the fourth optical paths, respectively, by temperature control. A first optical coupler couples optical signals transmitted via the third and the fifth optical paths. A second optical coupler couples optical signals transmitted via the fourth and the sixth optical paths. Photodetectors convert the optical signals from the optical couplers into electrical signals.Type: GrantFiled: November 30, 2005Date of Patent: November 3, 2009Assignee: Fujitsu LimitedInventors: Kazuo Hironishi, Takeshi Hoshida
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Patent number: 7603044Abstract: A system and method are provided for calibrating orthogonal polarity in a multichannel optical transport network (OTN) receiver. The method accepts a composite signal and separates the polarization of the signal into a pair of 2n-phase shift keying (2n-PSK) modulated input signals via Ix and Qx optical signal paths, where n?1. Likewise, a pair of 2p-PSK modulated input signals are accepted via Iy and Qy optical signal paths where p?1. Polarization-adjusted I?x, Q?x, I?y, and Q?y signals are generated. An average magnitude is compared to either 2×the absolute magnitude of (I?x and Q?x), or 2×the absolute magnitude of (I?y and Q?y). The average magnitude value can be used that is either 2×(a predetermined peak signal amplitude), or the sum of the absolute magnitudes of (I?x and Q?x) and (I?y and Q?y). The polarization-adjusted I?x, Q?x, I?y, and Q?y signals are modified until the magnitude comparison is about zero.Type: GrantFiled: December 3, 2008Date of Patent: October 13, 2009Assignee: Applied Micro Circuits CorporationInventors: Keith Conroy, Omer Acikel
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Patent number: 7599630Abstract: A method and system of coherent detection of optical signals. The system utilizes a digital signal processor to recover an incoming optical signal. The system employs a local oscillator, which does not need to be phase locked to the signal. The signal may be consistently recovered, even when the polarization state varies over time. Additionally, the signal may be recovered when it comprises two channels of the same wavelength that are polarization multiplexed together. In addition, any impairment to the signal may be reversed or eliminated.Type: GrantFiled: November 28, 2008Date of Patent: October 6, 2009Inventor: Michael George Taylor
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Patent number: 7529490Abstract: In an optical receiver according to the present invention, an input signal light subjected to the differential quadrature phase shift keying (DQPSK) is incident on a PANDA type fiber in a linearly polarized state by 45°, so that a delay time difference corresponding to one symbol is generated between orthogonal polarization components in the DQPSK signal light, and then, the signal light is branched by a half mirror into two, to be sent to first and second paths respectively, thereby giving, by a ¼ wave plate disposed on one of the paths, a relative birefringent amount difference of ?/2 between the lights propagated through the respective paths. Then, each of the lights propagated through the first and second paths is separated into two orthogonal polarization components by a polarization beam splitter, and the respective polarization components are received by a differential reception circuit so that in-phase components and quadrature components in the DQPSK signal are demodulated.Type: GrantFiled: April 29, 2005Date of Patent: May 5, 2009Assignee: Fujitsu LimitedInventor: Takeshi Hoshida
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Patent number: 7529481Abstract: An optical data signal can be sampled by linearly combining the optical data signal with optical sampling pulses, and delivering the combination to first and second balanced detectors. The optical data signal and the optical sampling pulse are configured to have a first phase difference at the first balanced detector and a second phase difference at the second balanced detector. Typically, a difference between the first phase difference and the second phase difference is configured to be about 90 degrees. In-phase and quadrature balanced detector outputs can be combined as a sum of squares to produce a linear sampling signal representative of data signal intensity, and the sample pulses can be configured to temporally step through the optical data signal so that a sampled representation of the optical data signal is obtained.Type: GrantFiled: March 15, 2004Date of Patent: May 5, 2009Assignees: State of Oregon Acting By and Through the State Board of Higher Education on Behalf of The University of Oregon, Lucent TechnologiesInventors: Christopher R. Doerr, Christophe J. Dorrer, Daniel C. Kilper, Michael G. Raymer, Howard R. Stuart, Peter J. Winzer
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Publication number: 20090074427Abstract: Digital compensation of the polarization-mode dispersion (PMD) effects experienced by an optical signal in a transmission link is achieved. A digital representation of the optical fields of two orthogonal polarization components of an optical signal, defined by a polarization beam splitter (PBS), is first obtained. The fiber transmission link is treated as a concatenation of multiple virtual PMD segments, each having two specific principle-state-of-polarization (PSP) axes and causing a differential group-delay (DGD) and a phase delay between two signal components that are polarized along the two PSP axes. The best guesses of the parameters of the PMD segments and the relative orientation between the PSP axes of the last PMD segment and the characteristic polarization axes of the PBS are dynamically obtained. The digital representation of at least one generic component of the field of the optical signal is then computed through matrix operations by using the best guesses.Type: ApplicationFiled: May 9, 2008Publication date: March 19, 2009Inventor: Xiang Liu
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Publication number: 20090047030Abstract: In order to reduce the size and simplify the structure of a coherent light receiver, the coherent light receiver includes an optical mixer for coupling local oscillator light and reception signal light, a photoelectric converter for photoelectrically converting light coupled in the optical mixer, a reception data processing unit for extracting reception data included in the reception signal light through digital signal processing for processing the coupled signal converted into an electrical signal by the photoelectric converter, based on a first clock, and a modulator for modulating the local oscillator light or the reception signal light inputted to the optical mixer respectively, by using a clock phase-synchronized with the first clock used for the digital signal processing in the reception data processing unit.Type: ApplicationFiled: July 30, 2008Publication date: February 19, 2009Applicant: Fujitsu LimitedInventor: Takeshi Hoshida
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Patent number: 7486895Abstract: The present invention includes apparatus and method of a variable step size dithering control algorithm for polarization mode dispersion controllers (PMDCs). The dithering step size of the PCs is adjusted according to the feedback signal including degree of polarization (DOP).Type: GrantFiled: December 13, 2005Date of Patent: February 3, 2009Assignee: Alcatel-Lucent USA Inc.Inventors: Dieter Werner, Chongjin Xie
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Patent number: 7486898Abstract: A receiver (10) for an optical signal containing a time jitter and a time-varying distortion caused by a periodic polarization scrambled signal comprises at least one decision gate (11) and a clock recovery module (13) providing a clock signal (C) recovered from the optical signal to the at least one decision gate (11). The receiver (10) further comprises a scrambling frequency generator (16) synchronized to the scrambling frequency and phase of the polarization scrambled signal, a jitter function generator (17) generating a clock phase control signal (??b) reproducing the time jitter, and at least one clock phase modulator (14) modulating the phase of the clock signal (C) according to the clock phase control signal (??b).Type: GrantFiled: December 8, 2005Date of Patent: February 3, 2009Assignee: AlcatelInventor: Henning Bülow
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Patent number: 7483642Abstract: A receiver for an OTDM/PDM pulse train (10) in which the pulses (12) have alternating polarizations (P1, P2) has a polarization insensitive optical switch (16; 161, 162, 163, 164) for isolating optical pulses (10?) within the pulse train (10), and a polarization selective element (17) for separating from the isolated pulses (10?) at least one component that has a single polarization. This allows to considerable relax the constraints posed on the switch since components in the isolated pulses that result from interchannel interference can, at least to a large extent, be eliminated by the subsequent polarization selective element (17).Type: GrantFiled: October 31, 2003Date of Patent: January 27, 2009Assignee: AlcatelInventors: Michael Schmidt, Eugen Lach