Finisar Corporation

Optium Corporation

Optium Coporation

Heider Naim Ereifej

Mark Colyar

Suhas P Bhandare

Ihab E Khalouf

Peter Hallemeier

Kyu Kim

Eitan Gertal

John J DeAndrea

Shalva Ben-Ezra

Er'el Granot

Sagie Tsadka

Terence D Grenda

Mark Coylar

David Meloche

Yinnon Stav

John L Fiorillo

Chris Stook

Eitan Gertel

A method and apparatus for characterizing and compensating optical impairments in an optical transmitter includes operating an optical transmitter comprising a first and second parent MZ, each comprising a plurality of child MZ modulators that are biased at respective initial operating points. An electro-optic RF transfer function is generated for each of the plurality of child MZ modulators. Curve fitting parameters are determined for each of the plurality of electro-optic RF transfer functions and operating points of each child MZ modulator are determined using the curve fitting parameters. An IQ power imbalance is determined using the curve fitting parameters. Initial RF drive power levels are determined that compensate for the determined IQ power imbalance. The XY power imbalance is determined for initial RF drive power levels using the curve fitting parameters. The operating RF drive powers are determined that at least partially compensate for the first and second IQ power imbalances and for the XY power imbalance for the optical transmitter. An optical signal comprising a Nyquist-pulse-shape is generated at an output of the optical transmitter.

Method and apparatus for characterization and compensation of optical impairments in InP-based optical transmitter

A method and apparatus for characterizing and compensating optical impairments in an optical transmitter includes operating an optical transmitter comprising a first and second parent MZ, each comprising a plurality of child MZ modulators that are biased at respective initial operating points. An electro-optic RF transfer function is generated for each of the plurality of child MZ modulators. Curve fitting parameters are determined for each of the plurality of electro-optic RF transfer functions and operating points of each child MZ modulator are determined using the curve fitting parameters. An IQ power imbalance is determined using the curve fitting parameters. Initial RF drive power levels are determined that compensate for the determined IQ power imbalance. The XY power imbalance is determined for initial RF drive power levels using the curve fitting parameters. The operating RF drive powers are determined that at least partially compensate for the first and second IQ power imbalances and for the XY power imbalance for the optical transmitter.

A DP-QPSK optical transmitter includes an outer MZM comprising a first parent MZM comprising a first child MZM and a second child MZM that modulates a QPSK signal with a first polarization. A second parent MZM includes a first child MZM and a second child MZM that modulates a QPSK signal with a second polarization. The outer Mach-Zehnder modulator multiplexes the first and second polarization embedded into a dual-polarization QPSK signal generation. A first optical detector detects the QPSK signal generated by the first parent MZM with the first polarization. A second optical detector optical detects the QPSK signal generated by the second parent Mach-Zehnder modulator with the second polarization. A bias control circuit generates bias signals on at least one output that stabilize the DP-QPSK signal in response to signals generated by the first and second optical detector using electrical time division multiplexing.

Method and apparatus for stabilization of optical transmitter

Embodiments include a method and apparatus used for automatic bias stabilization of a DP IQM based on MZM for transmitting DP-QPSK optical data and/or DP-16QAM optical data. The apparatus simultaneously dithers DC-bias voltages of in-phase child, quadrature-phase child, and parent MZMs with three different dither patterns in time-domain which are mutually orthogonal to each other in the frequency-domain for X and Y polarization IQ modulators. Tap monitor photodiodes detect an interference term between these three dither patterns for each polarization. The interference term is sampled using an ADC in the time domain. The time-synchronous detection method may solve a set of three simultaneous linear partial differential equations with three unknowns to compute controlled DC-bias voltages to set on the respective MZM with a solution set which may iteratively converge to a unique solution, thereby biasing the child MZM in dual-polarization IQM to transmission minimum and parent MZM in quadrature transmission.

Automatic bias stabilization of dual-polarization in-phase and quadrature optical modulator

A DPSK/DQPSK receiver includes an optical splitter that separates the received DPSK/DQPSK optical signal according to an optical power splitting ratio into a plurality of received optical signals. A plurality of optical filters passes a plurality of filtered received optical signals. A plurality of optical detectors generates a plurality of electrical detection signals, each with a power that is related to a power of a respective filtered optical signal. A plurality of amplifiers generates a plurality of amplified electrical signals. At least one electrical signal combiner combines the plurality of amplified electrical detection signals generated by the plurality of optical amplifiers into a combined reception signal.

Method and apparatus for demodulating and regenerating phase modulated optical signals

A cable television (CATV) optical transmitter includes a tunable laser having a phase bias input and a gain bias input. The tunable laser generates an optical beam at an output. A semiconductor optical amplifier includes an electrical bias input and an optical input that is optically coupled to the output of the tunable laser. The semiconductor amplifier amplifies the optical beam generated by the tunable laser. An integrated balanced modulator includes an electrical modulation input that receives analog CATV signals and an optical input that is connected to the output of the semiconductor amplifier. A third order pre-distortion circuit includes an output that is electrically connected to a modulation input of the integrated balanced modulator. The 3order pre-distortion circuit generates a signal that, when combined with the analog CATV modulation signal, at least partially cancels third order distortions that are introduced during modulation.

Integrated laser and modulator transmitter for CATV applications

An optical communications system includes an optical transmitter that generates a modulated optical signal at an output. The modulated optical signal propagates through an optical link where the dispersion of the optical link is imprinted onto an optical spectrum of the modulated optical signal. A demodulator receives the modulated optical signal and filters at least a portion of the optical spectrum with the imprinted dispersion of the optical link, thereby mitigating effects of dispersion in the modulated optical signal and generating a demodulated optical signal at an output. An optical detector generates an electrical data signal from the demodulated optical signal.

Method and apparatus for dispersion mitigation in optical links

An optical receiver includes an optical detector having an input that is positioned to detect an optical data signal. The optical detector generates a voltage at an output that is proportional to an optical intensity of the optical data signal. A differential amplifier includes a data input that is electrically connected to the output of the optical detector and a decision threshold voltage signal input. The differential amplifier generates a data signal at a data output and an inverse data signal at a data_bar output. A decision threshold voltage signal generator includes an output that is coupled to the decision threshold voltage signal input of the differential amplifier. The decision threshold voltage signal generator generates a decision threshold voltage signal having an amplitude that causes the differential amplifier to maintain a substantially constant differential voltage between the data signal and the inverse data signal generated.

Optical receiver with threshold voltage compensation

A multi-mode optical fiber link is described that includes a single-mode optical fiber having an input that receives an optical signal for transmission through the multi-mode optical fiber link. A first spatial mode converter is coupled to the single-mode optical fiber. The first spatial mode converter conditions a modal profile of the optical signal for propagation through a multi-mode optical fiber. A multi-mode optical fiber is coupled to an output of the first spatial mode converter. A second spatial mode converter is coupled to an output of the multi-mode optical fiber. The second spatial mode converter reduces a number of optical modes in the optical signal. Both the first and the second spatial mode converters increase an effective modal bandwidth of the optical signal propagating through an output of the second spatial mode converter.

Optical fiber transmission system with increased effective modal bandwidth transmission

An optical transmitter for an optical fiber transmission system is described. The optical transmitter includes an optical source that generates an optical signal having a wavelength at an output. An optical intensity modulator modulates the optical signal with an electrical modulation signal to generate a modulated optical signal at an output. At least one parameter of the optical intensity modulator is chosen to suppress at least one of phase and sideband information in the modulated optical signal. An optical fiber is coupled to the output of the optical intensity modulator. The suppression of the at least one of the phase and the sideband information in the modulated optical signal increases an effective modal bandwidth of the optical fiber.

Optical transmitter for increased effective modal bandwidth transmission

A multi-mode optical fiber link is described. The multi-mode optical fiber link includes a first spatial mode converter that is coupled to a first single mode optical fiber. The first spatial mode converter conditions a modal profile of an optical signal propagating from the single mode optical fiber to the first spatial mode converter. A multi-mode optical fiber is coupled to the first spatial mode converter. A second spatial mode converter is coupled to an output of the multi-mode optical fiber and to a second single mode optical fiber. The second spatial mode converter reduces a number of optical modes in the optical signal. Both the first and the second spatial mode converters increase an effective modal bandwidth of the optical signal.

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Chalfont, PA, United States of America

Heider Naim Ereifej