Patents Examined by Luis Garcia
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Patent number: 7266309Abstract: The present invention relates to an apparatus and method for stabilizing a bias voltage for a pulse generating modulator, which can automatically detect an optimal bias voltage for an external modulator, which is used in RZ or CSRZ modulation of an optical transmission signal using NRZ data to generate a reference pulse optical signal, and maintain the optimal bias voltage. In the bias voltage stabilizing method of the present invention, an output signal of the external modulator, to which the bias voltage to be stabilized is applied, is detected, a drive clock signal applied to the external modulator is detected, a mean output value of the products obtained by the multiplication of the output signal and the clock signal is periodically examined, and the bias voltage is adjusted so that the mean output value becomes “0”.Type: GrantFiled: April 16, 2004Date of Patent: September 4, 2007Assignee: Electronics and Telecommunications Research InstituteInventors: Youn Seon Jang, Kwang Joon Kim, Jin Soo Han
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Patent number: 7266300Abstract: A bi-directional path switched ring optical transmission node has simple configuration which reduces the influence of a wave reflected by an obstacle on optical line.The BPSR optical transmission node connects to a first optical line through which an odd channel signal and an even channel signal are transmitted to and from the BPSR optical transmission node in direction opposite to each other. The BPSR optical transmission node further connects to a second optical line through which the odd channel signal and the even channel signal are transmitted from and to the BPSR optical transmission node in direction opposite to each other.Type: GrantFiled: June 10, 2003Date of Patent: September 4, 2007Assignee: Samsung Electronics Co., Ltd.Inventors: Sung-Kee Kim, Young-Hun Joo, Seong-Taek Hwang
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Patent number: 7245830Abstract: Apparatus and method for scheduling transmission of data bursts in an OBS network are described. One embodiment is a router in an OBS network, the router comprising a grouper module for collecting a group of BHPs arriving during a BHP collecting period and classifying each BHP of the group of BHPs into corresponding baskets depending on the data channel scheduling window of its corresponding data burst; a classifier and channel assignment module for assigning data bursts to appropriate data channels; and a channel scheduler for constructing an interval graph representing data bursts corresponding to BHPs classified in a single one of the baskets having overlapping segments on each data channel as adjacent vertices and scheduling data bursts on each data channel based on a process that finds a maximum number of non-adjacent vertices on the interval graph.Type: GrantFiled: April 17, 2003Date of Patent: July 17, 2007Assignee: Alcatel-LucentInventors: Saravut Charcranoon, Tarek S. El-Bawab, Jong-Dug Shin, Hakki Candan Cankaya
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Patent number: 7236701Abstract: The present invention provides a low-cost optical transmission system using a plurality of subscriber lines which is capable of efficiently utilizing an optical transmission path. A communication status observing section 116 in a transmitting device 1 classifies subscribers into a plurality of groups based on a communication status at each subscriber end, and outputs constellation level information and level information which are different for each group. For each constant cycle, a modulation control section 117 and a gain control section 118 respectively set a QAM constellation level and a signal level which are different for each group and used in a basic modulating section 103.Type: GrantFiled: August 27, 2003Date of Patent: June 26, 2007Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Toshihiko Yasue, Hiroyuki Sasai, Masaru Fuse
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Patent number: 7218865Abstract: A burst-mode optical receiver of a differential-output structure is disclosed.Type: GrantFiled: April 15, 2003Date of Patent: May 15, 2007Assignee: Samsung Electronics Co., Ltd.Inventors: Hee-Chan Doh, Hyeon-Cheol Ki, Yun-Je Oh, Gil-Yong Park, Tae-Sung Park, Shin-Hee Won
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Patent number: 7218852Abstract: A system and method for discovering lightpath information in an optical network is disclosed. A selected node is requested to provide lightpath information. The node, in turn, requests the other node of the optical network to provide channel attribute data. The node processes the channel attribute data of a plurality of nodes to determine the lightpath information.Type: GrantFiled: December 20, 2002Date of Patent: May 15, 2007Assignee: Ciena CorporationInventor: Anirban Sharma
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Patent number: 7215893Abstract: A fiber optic communication system is provided that includes a light source adapted to emit a system optical signal and an electrical signal source adapted to provide a data input electrical signal. Additionally, the fiber optic communication system includes a feed forward photonic modulation circuit adapted to receive the data input electrical signal and the system optical signal and output a final modulated optical signal substantially free from residual error.Type: GrantFiled: August 28, 2003Date of Patent: May 8, 2007Assignee: The Boeing CompanyInventor: Daniel N. Harres
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Patent number: 7212738Abstract: A redundant optical signal transmission and reception system enables information exchange via an optical communications network without data loss in the event of optical transmitter or receiver failure. In one embodiment, the redundant optical signal system includes a primary transmission link comprising a plurality of optical transmitters and a multiplexor for modulating and combining electrical signals into a primary multiplexed optical signal. In the event of failure of an optical transmitter, a backup transmission link is activated to compensate for the malfunctioning transmitter. The backup transmission link utilizes a backup optical transmitter to modulate the electric signal formerly received by the malfunctioning optical transmitter. The backup transmission link combines the backup optical signal with the primary multiplexed optical signal to form a complete optical signal for transmission over the optical network.Type: GrantFiled: April 23, 2003Date of Patent: May 1, 2007Assignee: Finisar CorporationInventor: Steve Wang
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Patent number: 7209662Abstract: The wavelength multiplex transmission device of the present invention includes a block band unit (block dispersion compensating unit etc.) for subjecting a plurality of signal lights of different wavelengths to dispersion compensation on a band basis and outputting the compensated signal lights, a CW light output unit (CW light source unit etc.) for outputting a CW light which supplements power of the signal light, a band multiplexing unit for multiplexing all the signal lights output from the block band unit together with the CW light output from the CW light output unit, and a total band optical amplifier for amplifying all the signal lights multiplexed by the band multiplexing unit in the lump and transmitting the amplified signal lights to a transmission path.Type: GrantFiled: November 29, 2002Date of Patent: April 24, 2007Assignee: NEC CorporationInventor: Yasuhisa Taneda
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Patent number: 7203428Abstract: The invention relates to the monitoring of polarization mode dispersion (PMD) using heterodyne detection for providing PMD compensation in optical networks, and an apparatus for monitoring PMD. In the present invention, a broadband PMD monitor is disclosed based on heterodyne detection with a tunable laser source which can be fed to a compensator such as an add/drop or other wavelength switch and polarization dependent attenuation means. A signal from a local oscillator is combined with an optical signal and the beat frequency amplitude and phase is analyzed for two orthogonal polarization states simultaneously to obtain a state of polarization. By averaging a plurality of polarization states within a channel, PMD can be estimated for compensation.Type: GrantFiled: June 10, 2003Date of Patent: April 10, 2007Assignee: JDS Uniphase CorporationInventors: Robert G. Waarts, Russell Chipman
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Patent number: 7203421Abstract: A multi-channel optical switching system particularly usable as a programmable optical add/drop multiplexer in a multi-wavelength communication system. The switching system uses a grating operating at Littrow that separates a multi-channel optical signal into a plurality of optical channels, and combines a plurality of optical channels into a multi-channel optical signal. The system also uses a plurality of optical ports optically coupled to the grating and a selecting device to select which optical channel is directed to which of the optical ports.Type: GrantFiled: September 30, 2002Date of Patent: April 10, 2007Assignee: Optical Research AssociatesInventor: James P. McGuire, Jr.
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Patent number: 7167654Abstract: Optical transmission equipment with more than one power supply which can, when turning on the power supplies, set predetermined function of a signal processing circuit after a predetermined time period after the last turn-on of the power supply and can enable the operation of a drive circuit of the light emitting device after an additional predetermined time period.Type: GrantFiled: April 17, 2003Date of Patent: January 23, 2007Assignee: OpNext Japan, Inc.Inventors: Shigeru Tokita, Tomokazu Tanaka, Cleitus Antony, Tarou Tonoduka, Masazumi Noguchi
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Patent number: 7068932Abstract: A method for automatic initialization of an optical network is provided. A network management system (NMS) performs remote determination of span losses and sets the operating points of network components. The initialization method comprises remotely and automatically setting target gains of optical amplifiers and signal power levels at transmitters and receivers to required operating values. The methods for initialization of the optical network of the embodiments include gain excursion minimization (GEM) for individual channels passing through amplifiers and/or pre-emphasis of the optical link, where channel powers at the transmitters are biased to compensate for the effects of optical amplifiers gain ripple.Type: GrantFiled: October 1, 2002Date of Patent: June 27, 2006Assignee: Tropic Networks Inc.Inventors: Ping Wai Wan, Derrick Remedios, Eddie Kai Ho Ng