Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The cascade of MZ interferometers, each having a free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. Another MZ interferometer in series with the cascade of interferometers including an asymmetric or variable coupler, is tuned to have low transmission at the center frequency of the selected optical channel.

Abstract: A technique for tuning a silicon photonics (SiP) based nested (parent/child) Mach-Zehnder modulator (MZM). The technique includes a sequence of applying dither tones on individual arms of the child MZMs, observing changes in the output of the MZM, and adjusting the MZM until reaching the null points for the child MZMs and the quad point for the parent MZM.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The cascade of MZ interferometers, each having a free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. Another MZ interferometer in series with the cascade of interferometers including an asymmetric or variable coupler, is tuned to have low transmission at the center frequency of the selected optical channel.

Abstract: A wavelength selective device including an arrayed waveguide grating is disclosed. The wavelength selective device includes a MEMS mirror, which couples light from an input port to an elongate aperture of an input star coupler or slab of the arrayed waveguide grating. A controller tilts the MEMS mirror in response to a sensed temperature change of the arrayed waveguide grating, thereby lessening a sensitivity of the arrayed waveguide grating to the temperature change. The MEMS mirror can also be tilted to shift wavelengths of the wavelength channels of the arrayed waveguide grating by pre-defined amounts upon receiving a corresponding remote command.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The cascade of MZ interferometers, each having a free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. Another MZ interferometer in series with the cascade of interferometers including an asymmetric or variable coupler, is tuned to have low transmission at the center frequency of the selected optical channel.

Abstract: An optical interferometer for demodulating a differential phase shift keying optical signal includes a planar lightwave circuit and at least one free space delay line optically coupled to the planar lightwave circuit. The planar lightwave circuit has a waveguide splitter, a waveguide coupler, and a phase adjuster. In operation, the splitter splits the optical signal into equal portions, the phase adjuster adjusts the relative phase of the optical signal portions, and the free space delay line provides one-bit delay between the portions of the optical signal. The delayed signals are mixed in the waveguide coupler. The free space delay line can be made variable for adjustment of the bit delay for operation at different bit rates, and/or for optimization of the interferometer performance.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The cascade of MZ interferometers, each having a free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. Another MZ interferometer in series with the cascade of interferometers including an asymmetric or variable coupler, is tuned to have low transmission at the center frequency of the selected optical channel.

Abstract: A tunable optical filter is configured to take point measurements at a few optical frequencies per frequency channel of a DWDM optical network. The measurement frequencies are shifted by pre-determined amounts relative to the optical frequency channel being characterized. Since the spectral shape of the tunable optical filter is known, the center optical frequency, the modulation bandwidth, and the total optical power of the channel can be obtained from as few as three optical measurements. The center optical frequency and the total optical power can be continuously monitored by providing a tunable filter stage coupled to an interleaver stage, and computing a ratio and a weighted sum the optical signals at the two outputs of the interleaver stage.

Abstract: A wavelength selective device including an arrayed waveguide grating is disclosed. The wavelength selective device includes a MEMS mirror, which couples light from an input port to an elongate aperture of an input star coupler or slab of the arrayed waveguide grating. A controller tilts the MEMS mirror in response to a sensed temperature change of the arrayed waveguide grating, thereby lessening a sensitivity of the arrayed waveguide grating to the temperature change. The MEMS mirror can also be tilted to shift wavelengths of the wavelength channels of the arrayed waveguide grating by pre-defined amounts upon receiving a corresponding remote command.

Abstract: A tunable optical filter is configured to take point measurements at a few optical frequencies per frequency channel of a DWDM optical network. The measurement frequencies are shifted by pre-determined amounts relative to the optical frequency channel being characterized. Since the spectral shape of the tunable optical filter is known, the center optical frequency, the modulation bandwidth, and the total optical power of the channel can be obtained from as few as three optical measurements. The center optical frequency and the total optical power can be continuously monitored by providing a tunable filter stage coupled to an interleaver stage, and computing a ratio and a weighted sum the optical signals at the two outputs of the interleaver stage.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter.

Abstract: An optical device for rearranging wavelength channels in an optical network is disclosed. The optical device has a wavelength selective coupler having one input port and a plurality of output ports coupled to a plurality of input ports of an optical grating demultiplexor such as an arrayed waveguide grating. The wavelength channels in each of the input ports are dispersed by the demultiplexor and are directed to a plurality of output ports of the optical grating demultiplexor. As a result, at least one wavelength channel at each of the input ports of the optical grating demultiplexor is coupled into a common output port. The optical device is useful in passive optical networks wherein a same demultiplexor is used for simultaneous multiplexing and demultiplexing of wavelength channels.

Abstract: An optical interferometer for demodulating a differential phase shift keying optical signal includes a planar lightwave circuit and at least one free space delay line optically coupled to the planar lightwave circuit. The planar lightwave circuit has a waveguide splitter, a waveguide coupler, and a phase adjuster. In operation, the splitter splits the optical signal into equal portions, the phase adjuster adjusts the relative phase of the optical signal portions, and the free space delay line provides one-bit delay between the portions of the optical signal. The delayed signals are mixed in the waveguide coupler. The free space delay line can be made variable for adjustment of the bit delay for operation at different bit rates, and/or for optimization of the interferometer performance.

Abstract: A scanning optical spectrometer with a detector array is disclosed, in which position of focused spot of light at the input of a dispersive element such as arrayed waveguide grating (AWG) with a slab input, is scanned using a micro-electro-mechanical (MEMS) tiltable micromirror so as to make the dispersed spectrum of light scan over the detector array coupled to the AWG. Sub-spectra recorded using individual detectors are concatenated by a processor unit to obtain the spectrum of input light.

Abstract: A scanning optical spectrometer with a detector array is disclosed, in which position of focused spot of light at the input of a dispersive element such as arrayed waveguide grating (AWG) with a slab input, is scanned using a micro-electro-mechanical (MEMS) tiltable micromirror so as to make the dispersed spectrum of light scan over the detector array coupled to the AWG. Sub-spectra recorded using individual detectors are concatenated by a processor unit to obtain the spectrum of input light.

Abstract: An optical device for rearranging wavelength channels in an optical network is disclosed. The optical device has a wavelength selective coupler having one input port and a plurality of output ports coupled to a plurality of input ports of an optical grating demultiplexor such as an arrayed waveguide grating. The wavelength channels in each of the input ports are dispersed by the demultiplexor and are directed to a plurality of output ports of the optical grating demultiplexor. As a result, at least one wavelength channel at each of the input ports of the optical grating demultiplexor is coupled into a common output port. The optical device is useful in passive optical networks wherein a same demultiplexor is used for simultaneous multiplexing and demultiplexing of wavelength channels.

Abstract: A method and an apparatus for calibrating a MEMS actuator of a hybrid MEMS-PLC optical switch or router is described. Two calibrating waveguides, embedded monolithically adjacent to the waveguides that provide the PLC output functions, are used for referencing a MEMS mirror tilt angle by maximizing optical coupling of light, reflected off the MEMS mirror, into one or each of the two calibrating waveguides. The input light is provided by either a waveguide carrying a live optical signal, or by a special input waveguide, coupled to an LED, for providing a calibrating light. Two emitting waveguides, embedded monolithically adjacent to the waveguides that provide the PLC input functions, can be used.

Abstract: A scanning optical spectrometer with a detector array is disclosed, in which position of focused spot of light at the input of a dispersive element such as arrayed waveguide grating (AWG) with a slab input, is scanned using a micro-electro-mechanical (MEMS) tiltable micromirror so as to make the dispersed spectrum of light scan over the detector array coupled to the AWG. Sub-spectra recorded using individual detectors are concatenated by a processor unit to obtain the spectrum of input light.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter.

Abstract: A scanning optical spectrometer with a detector array is disclosed, in which position of focused spot of light at the input of a dispersive element such as arrayed waveguide grating (AWG) with a slab input, is scanned using a micro-electro-mechanical (MEMS) tiltable micromirror so as to make the dispersed spectrum of light scan over the detector array coupled to the AWG. Sub-spectra recorded using individual detectors are concatenated by a processor unit to obtain the spectrum of input light.