Patents by Inventor Douglas McGhan
Douglas McGhan 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: 8983309Abstract: A transmitter in an optical communications system includes a digital signal processor for processing a data signal to generate a sample stream encoding successive symbols in accordance with a constrained phase modulation scheme having a constellation of at least two symbols and a modulation phase constrained to a phase range spanning less than 4?. A digital-to-analog converter converts the sample stream into a corresponding analog drive signal. A finite range phase modulator modulates a phase of a continuous wavelength channel light in accordance with the analog drive signal, to generate a modulated channel light for transmission through the optical communications system. A receiver in the optical communications system includes an optical stage for detecting phase and amplitude of the modulated channel light and for generating a corresponding sample stream, and a digital signal processor for processing the sample stream to estimate each successive symbol of the modulated channel light.Type: GrantFiled: February 13, 2012Date of Patent: March 17, 2015Assignee: Ciena CorporationInventors: James Harley, Douglas McGhan, Shahab Oveis Gharan, Kim B. Roberts, Mark Rollins
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Publication number: 20130209089Abstract: A transmitter in an optical communications system includes a digital signal processor for processing a data signal to generate a sample stream encoding successive symbols in accordance with a constrained phase modulation scheme having a constellation of at least two symbols and a modulation phase constrained to a phase range spanning less than 4?. A digital-to-analog converter converts the sample stream into a corresponding analog drive signal. A finite range phase modulator modulates a phase of a continuous wavelength channel light in accordance with the analog drive signal, to generate a modulated channel light for transmission through the optical communications system. A receiver in the optical communications system includes an optical stage for detecting phase and amplitude of the modulated channel light and for generating a corresponding sample stream, and a digital signal processor for processing the sample stream to estimate each successive symbol of the modulated channel light.Type: ApplicationFiled: February 13, 2012Publication date: August 15, 2013Applicant: CIENA CORPORATIONInventors: James HARLEY, Douglas MCGHAN, Shahab OVEIS GHARAN, Kim B. ROBERTS, Mark ROLLINS
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Patent number: 8059970Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.Type: GrantFiled: July 6, 2010Date of Patent: November 15, 2011Assignee: Ciena CorporationInventors: James Harley, Douglas McGhan, Mohammad Sotoodeh, Anant Grewal, Mark Hawryluck
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Publication number: 20100272446Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.Type: ApplicationFiled: July 6, 2010Publication date: October 28, 2010Applicant: CIENA CORPORATIONInventors: James Harley, Douglas McGhan, Mohammad Sotoodeh, Anant Grewal, Mark Hawryluck
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Patent number: 7787778Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.Type: GrantFiled: February 28, 2005Date of Patent: August 31, 2010Assignee: Ciena CorporationInventors: James Harley, Douglas McGhan, Mohammad Sotoodeh, Anant Grewal, Mark Hawryluck
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Publication number: 20060127104Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.Type: ApplicationFiled: February 28, 2005Publication date: June 15, 2006Applicant: Nortel Networks LimitedInventors: James Harley, Douglas McGhan, Mohammad Sotoodeh, Anant Grewal, Mark Hawryluck
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Patent number: 7023601Abstract: A method for modulating the E-field of an optical carrier signal utilizes a Mach-Zehnder modulator having a pair of independently controllable branches. A pair of independent branch drive signals VL(t) and VR(t) are derived. Each branch of the MZ modulator is driven with a respective one of the independent branch drive signals. By this means, a low cost conventional MZ modulator (interferometer) can be used to perform complex modulation of the E-field of the optical carrier. In some embodiments, this functionality is used to facilitate precompensation of optical impairments of an optical communications system.Type: GrantFiled: October 3, 2003Date of Patent: April 4, 2006Assignee: Nortel Networks LimitedInventors: Douglas McGhan, Maurice O'Sullivan, Yves Beaulieu
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Publication number: 20050007642Abstract: A method for modulating the E-field of an optical carrier signal utilizes a Mach-Zehnder modulator having a pair of independently controllable branches. A pair of independent branch drive signals VL(t) and VR(t) are derived. Each branch of the MZ modulator is driven with a respective one of the independent branch drive signals. By this means, a low cost conventional MZ modulator (interferometer) can be used to perform complex modulation of the E-field of the optical carrier. In some embodiments, this functionality is used to facilitate precompensation of optical impairments of an optical communications system.Type: ApplicationFiled: October 3, 2003Publication date: January 13, 2005Applicant: NORTEL NETWORKS LIMITEDInventors: Douglas McGhan, Maurice O'Sullivan, Yves Beaulieu