Patents by Inventor Jithamithra Sarathy
Jithamithra Sarathy has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7319555Abstract: Monitoring of the input power is performed on-chip and is used to monitor and maintain performance, detect failure and trigger network protection strategies. An optical power-monitoring technique uses a photodetector monolithically integrated with the semiconductor optical amplifier—Mach-Zehnder interferometer circuit to monitor the P2R device and keep the output stable while the input power varies.Type: GrantFiled: April 27, 2006Date of Patent: January 15, 2008Assignee: Alphion CorporationInventors: Ganesh Lakshminarayana, Ruomei Mu, Hongsheng Wang, Jithamithra Sarathy, Boris Stefanov
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Patent number: 7239768Abstract: A integrated optical circuit comprises an interferometer having a first optical path and a second optical path configured for regenerating an input signal entering the first path by interference at a first coupler between continuous wave (CW) signals from the two optical paths, and a third optical path configured such that a canceling signal passing therethrough cancels, at a second coupler, a traveling signal from the first arm. When the device is operated in a counter-propagative mode, the traveling signal is the CW signal from the first arm. When the device is operated in a co-propagative mode, the traveling signal is the input signal from the first arm.Type: GrantFiled: June 2, 2005Date of Patent: July 3, 2007Assignee: Alphion CorporationInventors: Ganesh Lakshminarayana, Jithamithra Sarathy, Boris Stefanov
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Patent number: 7203427Abstract: A system, method and device for AO2R is presented. The AO2R system presented is redundant, containing multiple pathways for the input and output signals to travel. The system carries out both the regeneration and reshaping functions in the optical domain, and returns a clean output signal at the same bit rate and in the same format as the input signal, on a wavelength of choice. As an all optical device, the apparatus is bit rate and format transparent, and requires no optical-electrical-optical conversion. The system's built in redundancy and symmetry allows less than perfect yields on components to be tolerated, thus increasing the utility of devices manufactured with less than perfect yields. In alternative embodiments the redundancy aspect of the invention can be extended to any optical signal processing device, thus facilitating high availability optical signal processing.Type: GrantFiled: May 15, 2002Date of Patent: April 10, 2007Assignee: Alphion CorporationInventors: Gaurav Naik, Jithamithra Sarathy, Michael Evans, David Lidsky
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Patent number: 7190909Abstract: Method and apparatus are presented for the generation and detection of maintenance signals in an optical data network. The maintenance signals are such that they can be read both by high bit-rate and low bit-rate receivers. Detection of the maintenance signals occurs in two stages. In a low bit-rate first stage each nodal input port is sampled in a round robin fashion to detect the presence of a maintenance signal. In a high bit-rate second stage the maintenance signal is verified and read by a high speed receiver, along with other high bit-rate information transmitted with it. One second stage high speed receiver is shared among M input channels for cost and circuit efficiency.Type: GrantFiled: June 14, 2002Date of Patent: March 13, 2007Assignee: Alphion CorporationInventors: Jayanta Das, Ganesh Lakshminarayana, Kuo-Ming Lee, Roman Antosik, Scott Kaminski, Jithamithra Sarathy, Boris Stefanov, Ronald Simprini, Bharat Dave
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Publication number: 20070008613Abstract: Monitoring of the input power is performed on-chip and is used to monitor and maintain performance, detect failure and trigger network protection strategies. An optical power-monitoring technique uses a photodetector monolithically integrated with the semiconductor optical amplifier—Mach-Zehnder interferometer circuit to monitor the P2R device and keep the output stable while the input power varies.Type: ApplicationFiled: April 27, 2006Publication date: January 11, 2007Inventors: Ganesh Lakshminarayana, Ruomei Mu, Hongsheng Wang, Jithamithra Sarathy, Boris Stefanov
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Method and apparatus for bit-rate and format insensitive performance monitoring of lightwave signals
Patent number: 7009210Abstract: A method and apparatus for a tunable optical spectrum analyzer that can measure the optical spectrum of a demultiplexed DWDM signal are presented. The signal level and Optical Signal to Noise Ratio (OSNR) of an individual channel of the DWDM signal can be obtained from the measured optical spectrum. The device employs a rapid tuning and detection technique to obtain the optical spectrum of the incoming signal. In a preferred embodiment the apparatus is fabricated on a single chip resulting in a compact measurement device. Using the device of the preferred embodiment, single channel OSNR can be determined in as small a time interval as approximately 225 microseconds. Using an array of these devices an entire DWDM mixed signal can be monitored as to OP and OSNR in the same time interval.Type: GrantFiled: May 9, 2001Date of Patent: March 7, 2006Assignee: Alphion CorporationInventors: Jithamithra Sarathy, Chinnabbu Ekambaram, David Lidsky, Bharat Dave, Boris Stefanov, Tan B. Thai, Ronald Simprini, Julio Martinez, Gaurav Naik -
Publication number: 20060018587Abstract: A integrated optical circuit comprises an interferometer having a first optical path and a second optical path configured for regenerating an input signal entering the first path by interference at a first coupler between continuous wave (CW) signals from the two optical paths, and a third optical path configured such that a canceling signal passing therethrough cancels, at a second coupler, a traveling signal from the first arm. When the device is operated in a counter-propagative mode, the traveling signal is the CW signal from the first arm. When the device is operated in a co-propagative mode, the traveling signal is the input signal from the first arm.Type: ApplicationFiled: June 2, 2005Publication date: January 26, 2006Inventors: Ganesh Lakshminarayana, Jithamithra Sarathy, Boris Stefanov
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Patent number: 6804426Abstract: A single device for amplifying and multiplying an optical signal is presented. The device is an InP-semiconductor-based amplified multimode interferometer. The three main sections of the device are an input port, an interference and amplification region and N output ports. The input port is a single channel waveguide. The interference and amplification section supports a large number of modes which interfere with one another. By carefully choosing the length of the interference/amplification region to correspond to the constructive interference condition for N equally spaced channel modes, we can reproduce N amplified signals. In an alternate embodiment, by shaping the gain region into a cross pattern, corner reflections and consequent side channel signal distortion in the output can be minimized.Type: GrantFiled: May 15, 2002Date of Patent: October 12, 2004Assignee: Alphion CorporationInventors: David Lidsky, Jithamithra Sarathy
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Patent number: 6766113Abstract: A facility is provided to allow a supervisory message to quickly propagate through a transmission network without delay. Specifically, a supervisory message is quickly routed from one node to a next node by (a) splitting the control channel signal carrying the supervisory message at a receiving node, (b) sending one of the split control channel signals to an output via switchable apparatus for immediate transmission the next node and (c) sending the other split signal to a controller for analysis. If the controller invokes a predetermined procedure as a result of the content of the message, e.g., invokes protection switching, then the controller forms a supervisory message identifying the invoked procedure, operates the switchable apparatus so that the message identifying the invoked procedure may be routed to the output in place of the split channel signal message.Type: GrantFiled: June 16, 2000Date of Patent: July 20, 2004Assignee: Lucent Technologies Inc.Inventors: Daniel Y. Al-Salameh, Mario F. Alvarez, David S. Levy, Jithamithra Sarathy, Anastasios Tzathas
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Patent number: 6678086Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.Type: GrantFiled: July 15, 2002Date of Patent: January 13, 2004Assignee: Alphion CorporationInventors: Bharat Dave, Doruk Engin, Kwang Kim, Mohammad Laham, Julio Martinez, Olga Nedzhvetskaya, Jithamithra Sarathy, Ronald Simprini, Boris Stefanov, Tan Buu Thai
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Patent number: 6671467Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.Type: GrantFiled: July 15, 2002Date of Patent: December 30, 2003Assignee: Alphion CorporationInventors: Bharat Dave, Doruk Engin, Kwang Kim, Mohammad Laham, Julio Martinez, Olga Nedzhvetskaya, Jithamithra Sarathy, Roanld Simprini, Boris Stefanov, Tan Buu Thai
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Patent number: 6636318Abstract: A method and system for AO3R functionality is presented. The system includes an AO2R device followed by an AOCR clock recovery module and an AOR retiming device. The AOR retiming device takes as input a recovered clock signal extracted from the output of the AO2R by the AOCR clock recovery module. The output is the recovered clock signal gated by the regenerated and reshaped input signal, and a monitor circuit is used to set the optimum operations of the retiming device. In a first embodiment the output of the AOR retiming device is fed to an AOC code and wavelength conversion output stage, which returns the signal to the NRZ coding, on a service wavelength converted to match the fixed wavelength connection with the DWDM transmission system. In a second embodiment the code conversion is incorporated into the AOR retiming device, and wavelength conversion is accomplished in the AOCR clock recovery device.Type: GrantFiled: October 5, 2001Date of Patent: October 21, 2003Assignee: Alphion Corp.Inventors: Jithamithra Sarathy, Bharat Dave, Boris Stefanov, Ronald Simprini, Tan B. Thai, Roman Antosik, Aleksandr Miglo, Olga Nedzhvetska, Kwang Kim, Doruk Engin
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Patent number: 6624924Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.Type: GrantFiled: July 15, 2002Date of Patent: September 23, 2003Assignee: Alphion Corp.Inventors: Bharat Dave, Doruk Engin, Kwang Kim, Mohammad Laham, Julio Martinez, Olga Nedzhvetskaya, Jithamithra Sarathy, Ronald Simprini, Boris Stefanov, Tan Buu Thai
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Patent number: 6594072Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.Type: GrantFiled: July 15, 2002Date of Patent: July 15, 2003Assignee: Alphion CorporationInventors: Bharat Dave, Doruk Engin, Kwang Kim, Julio Martinez, Olga Nedzhvetskaya, Jithamithra Sarathy, Ronald Simprini, Boris Stefanov, Tan Buu Thai
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Patent number: 6563621Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.Type: GrantFiled: May 4, 2001Date of Patent: May 13, 2003Assignee: Alphion CorporationInventors: Bharat Dave, Doruk Engin, Kwang Kim, Mohammad Laham, Julio Martinez, Olga Nedzhvetskaya, Jithamithra Sarathy, Ronald Simprini, Boris Stefanov, Tan Buu Thai
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Publication number: 20030067648Abstract: A method and apparatus are presented for implementing maintenance signaling in an optical data network, said method comprising the use of a finite set of optical symbols to distinguish between different classes of failures. The method is format and bit rate transparent, and a network element does not need to read bits to interpret a signaling message. Faults protected within the network are distinguished from faults originating outside the network, and power glitches are filtered out of incoming alarm signals originating outside the network.Type: ApplicationFiled: April 8, 2002Publication date: April 10, 2003Inventors: Roman Antosik, Jayanta Das, Bharat Dave, Kuo-Ming Lee, David Lowe, Kwang Kim, Jithamithra Sarathy, Ronald Simprini, Boris Stefanov, Tan Thai, Wai-Ching Yu
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Publication number: 20030043428Abstract: A method and apparatus are presented for a tunable device for measuring the optical spectrum of a DWDM signal on a per channel basis. The device is an InP-semiconductor based tunable ring resonator. In a preferred embodiment the typical size of the chip is approximately 250&mgr;m×250&mgr;m. The three main sections of the device comprise a straight input passive waveguide, a straight output absorbing waveguide, and a tunable ring resonator. The ring resonator sets up a wavelength selective resonant cavity, allowing measurement of OP and OSNR across the free spectral range of the device, centered at a nominal service wavelength. In the preferred embodiment, the device can measure the OP and OSNR of an arbitrary demultiplexed DWDM signal, with a measurement time of approximately 225 microseconds. Inasmuch as the device is simply measuring optical performance parameters within a particular frequency (i.e.Type: ApplicationFiled: August 21, 2002Publication date: March 6, 2003Inventors: David Lidsky, Jithamithra Sarathy
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Publication number: 20030016654Abstract: Method and apparatus are presented which define generic cross-connect primitives that enable the implementation of 1+1 protection in a mesh configured optical network. Such primitives are capable of supporting both 1+1 network protection as well as 1+1 client/access protection, or both. Further, the invention supports multicast applications at no additional architectural cost.Type: ApplicationFiled: June 14, 2002Publication date: January 23, 2003Inventors: Jayanta Das, Ganesh Lakshminarayana, Kuo-Ming Lee, Roman Antosik, Scott Kaminski, Jithamithra Sarathy, Boris Stefanov, Ronald Simprini, Bharat Dave
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Publication number: 20030011836Abstract: Method and apparatus are presented for the generation and detection of maintenance signals in an optical data network. The maintenance signals are such that they can be read both by high bit-rate and low bit-rate receivers. Detection of the maintenance signals occurs in two stages. In a low bit-rate first stage each nodal input port is sampled in a round robin fashion to detect the presence of a maintenance signal. In a high bit-rate second stage the maintenance signal is verified and read by a high speed receiver, along with other high bit-rate information transmitted with it. One second stage high speed receiver is shared among M input channels for cost and circuit efficiency.Type: ApplicationFiled: June 14, 2002Publication date: January 16, 2003Inventors: Jayanta Das, Ganesh Lakshminarayana, Kuo-Ming Lee, Roman Antosik, Scott Kaminski, Jithamithra Sarathy, Boris Stefanov, Ronald Simprini, Bharat Dave
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Publication number: 20030002117Abstract: A system, method and device for AO2R is presented. The AO2R system presented is redundant, containing multiple pathways for the input and output signals to travel. The system carries out both the regeneration and reshaping functions in the optical domain, and returns a clean output signal at the same bit rate and in the same format as the input signal, on a wavelength of choice. As an all optical device, the apparatus is bit rate and format transparent, and requires no optical-electrical-optical conversion. The system's built in redundancy and symmetry allows less than perfect yields on components to be tolerated, thus increasing the utility of devices manufactured with less than perfect yields. In alternative embodiments the redundancy aspect of the invention can be extended to any optical signal processing device, thus facilitating high availability optical signal processing.Type: ApplicationFiled: May 15, 2002Publication date: January 2, 2003Inventors: Gaurav Naik, Jithamithra Sarathy, Michael Evans, David Lidsky