Abstract: Duobinary and NRZ modulation of an X-Gb/s optical signal is achieved with a lumped element InP Mach-Zehnder device configured to operate at X/k-Gb/s where k>1 and arranged in a push-pull configuration.

Abstract: A method and apparatus for receiving narrowband filtered optical PSK signals, including converting PSK optical signals into intensity-modulated signals at a receiver, and introducing a desired amplitude imbalance between the first and the second intensity-modulated signals to improve receiver performance.

Abstract: Duobinary and NRZ modulation of an X-Gb/s optical signal is achieved with a lumped element InP Mach-Zehnder device configured to operate at X/k-Gb/s where k>1 and arranged in a push-pull configuration.

Abstract: An apparatus and method for tunably delaying a signal and using that delayed signal in a duobinary transmitter is described. The transmitted duobinary signal is representative of the binary signal, and is formed by, among other things, introducing into a copy of the binary signal a delay that may be adjusted to be greater than or less than the bit period of the signal. Once the binary signal has been converted into a duobinary signal, it may then be converted into an optical duobinary signal. Alternatively, the conversion from binary to duobinary in accordance with the invention may be performed in the optical domain.

Abstract: A multi-channel optical equalizer for intersymbol interference mitigation compensates for single- or multi-wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer also compensates for overshoots and signal transition degradations in semiconductor optical amplifiers. The equalizer unit uses one control signal for magnitude and one to control signal phase. The equalizer includes a controllable coupling ratio coupler for splitting the light into two portions and a controllable interferometer having two arms, one arm having an additional delay which is equal to an integer multiple of 1/?f, where ?f is the channel spacing between adjacent wavelengths utilized in the optical system. The controllable interferometer has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

Abstract: A method and apparatus for receiving narrowband filtered optical PSK signals, including converting PSK optical signals into intensity-modulated signals at a receiver, and introducing a desired amplitude imbalance between the first and the second intensity-modulated signals to improve receiver performance.

Abstract: A method of and apparatus for optical signal dispersion compensation uses tunable optical (ODC) and electronic (EDC) dispersion compensation. The ODC provides significant first-order dispersion compensation, but leaves significant high-order dispersion and transmissivity ripple effects. The EDC is used to provide compensation for the high-order dispersion and transmissivity ripple from the ODC.

Abstract: A variable bandwidth hierarchical OADM apparatus and method handles different data rates, based on a waveband OADM and one or more wavelength OADMs in parallel. The wavelength OADM combines multiple adjacent channels with fine granularity up to the bandwidth of the waveband OADM. The wavebands and wavelengths to be passed, dropped, and added by the hierarchical OADM apparatus are all electronically selectable, hence no hardware modification is needed when the data rate is changed. The use of a coarse granularity waveband OADM and variable-bandwidth wavelength OADM with fine granularity enables our hierarchical OADM apparatus and method to provide a variable-bandwidth multi-granularity add/drop capability.

Abstract: An apparatus and method for tunably delaying a signal and using that delayed signal in a duobinary transmitter is described. The transmitted duobinary signal is representative of the binary signal, and is formed by, among other things, introducing into a copy of the binary signal a delay that may be adjusted to be greater than or less than the bit period of the signal. Once the binary signal has been converted into a duobinary signal, it may then be converted into an optical duobinary signal. Alternatively, the conversion from binary to duobinary in accordance with the invention may be performed in the optical domain.

Abstract: A multi-channel optical equalizer for intersymbol interference mitigation compensates for single- or multi-wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer also compensates for overshoots and signal transition degradations in semiconductor optical amplifiers. The equalizer unit uses one control signal for magnitude and one to control signal phase. The equalizer includes a controllable coupling ratio coupler for splitting the light into two portions and a controllable interferometer having two arms, one arm having an additional delay which is equal to an integer multiple of 1/?f, where ?f is the channel spacing between adjacent wavelengths utilized in the optical system. The controllable interferometer has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

Abstract: A variable bandwidth hierarchical OADM apparatus and method handles different data rates, based on a waveband OADM and one or more wavelength OADMs in parallel. The wavelength OADM combines multiple adjacent channels with fine granularity up to the bandwidth of the waveband OADM. The wavebands and wavelengths to be passed, dropped, and added by the hierarchical OADM apparatus are all electronically selectable, hence no hardware modification is needed when the data rate is changed. The use of a coarse granularity waveband OADM and variable-bandwidth wavelength OADM with fine granularity enables our hierarchical OADM apparatus and method to provide a variable-bandwidth multi-granularity add/drop capability.

Abstract: A multi-channel optical equalizer for intersymbol interference mitigation compensates for single- or multi- wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer compensates for overshoots and signal transition degradations in semiconductor optical amplifiers. The equalizer unit uses one control signal for magnitude and one to control signal phase. The equalizer includes a controllable coupling ratio coupler for splitting the light into two portions and a controllable interferometer having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&Dgr;f, where &Dgr;f is the channel spacing between adjacent wavelengths utilized in the optical system. The controllable interferometer has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

Abstract: An improved multi-channel optical equalizer method and apparatus for intersymbol interference mitigation compensates for single- or multi-wavelength channels simultaneously and requires few adjustable parameters. The optical equalizer can also compensate for overshoots and signal transition degradations of a semiconductor optical amplifier. The equalizer unit has only two control signals, one to control signal magnitude and one to control signal phase, yet it can still compensate many wavelength channels simultaneously. The equalizer includes a coupler with a controllable coupling ratio for splitting the light into two portions and a controllable interferometer means having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&Dgr;f, where &Dgr;f is the channel spacing between adjacent wavelengths utilized in the optical system.

Abstract: An improved multi-channel optical equalizer method and apparatus for intersymbol interference mitigation compensates many wavelength channels simultaneously and requires few adjustable parameters. The equalizer unit has only two control signals, one to control signal magnitude and one to control signal phase, yet it can still compensate many wavelength channels simultaneously. The equalizer includes a coupler with a controllable coupling ratio for splitting the light into two portions and a controllable interferometer means having two arms, one arm having an additional delay which is equal to an integer multiple of 1/&Dgr;f, where &Dgr;f is the channel spacing of the multiwavelength system. The controllable interferometer unit also has a controllable delay in a first or second arm for adjusting the relative phase of the light passing therethrough. A coupler combines the two signal portions from the first and second arms to form the equalized output signal.

Abstract: A photodetector and a method of manufacture therefor. The photodetector includes a waveguide located over a photodetector substrate and a resonant coupler located over and coupled to the waveguide. An index of refraction of the resonant coupler is greater than an index of refraction of the waveguide. The photodetector also includes an absorber located over and coupled to the resonant coupler, wherein the absorber has an index of refraction greater than the index of refraction of the resonant coupler.

Abstract: An optical device for coupling an optical signal to an optical detector is disclosed. The optical device includes a mode compression section disposed between an optical input source and a photodetector, which enables efficient coupling between the optical input source and the photodetector.

Abstract: A wavelength selective polarization beam device uses waveguide grating routers (WGRs) having birefringent grating waveguides. When the device is used as a splitter it separates different wavelength channels of a wavelength division multiplexed (WDM) signal as well as the orthogonal polarization components of each wavelength channel. Since the WGR device is reciprocal, it can also be used as a combiner to combine the orthogonal polarization components of each wavelength channel into a WDM signal.

Abstract: A high performance photodetector is integrated with a high performance modulator and a resistor on a single semiconductor substrate, all three sharing a common node. Voltage biases are applied to each of the diodes of the photodetector and modulator. As light is incident on the photodetector a current is generated which causes a voltage drop across the resistor. The voltage across the modulator then becomes the difference between its voltage bias and the voltage drop across the resistor. By properly selecting a resistor any desirable voltage swing is achieved without electrical amplifiers. Since the device is primarily optical and on a single semiconductor substrate, the device is independent of data rate, subject only to the inherent timing constant of the circuit.

Abstract: A direct detector uses optical amplification and resistors to eliminate the need for linear electrical amplifiers. The receives evenly splits an input light wave along a clock path and a data recovery path. Along the clock path a first photodetector detects the light wave. The input power induces a current across a first resistor in series with the photodetector giving rise to a voltage V which becomes the input voltage to the cock recovery device. The output from the clock recovery device is then split by an optical power splitter with one output to a decision circuit and another output optionally available for external use. Along the data path the light wave is split a second time and each of the two resultant paths are detected by a photodetector in series with a resistor. The decision circuit has input pins from each of the photodetectors to provide the data signal and its average DC voltage in lieu of the complement of the data signal as inputs to the decision circuit.