Abstract: A WSS device in which a VIPA is used as a spectral disperser. In an example embodiment, the VIPA is configured to produce two or more diffraction orders on the LCOS micro-display of the WSS device. The LCOS micro-display is configurable to independently process light corresponding to different diffraction orders. For example, the LCOS micro-display may be used to implement: (i) optical-signal switching by applying different relative phase shifts to light of different diffraction orders to cause constructive interference at a selected one of the optical ports of the WSS device; (ii) optical-signal splitting by steering light of different diffraction orders to at least two different selected optical ports of the WSS device; and (iii) controllable optical-signal attenuation by applying different relative phase shifts to different diffraction orders to control the relative degree of constructive and destructive interference at a selected one of the optical ports of the WSS device.

Abstract: An apparatus includes a TDM PON optical transceiver including a direct-detection optical receiver. The direct-detection optical receiver is configured to demodulate data from a temporal segment of a data modulated optical signal, wherein the optical carrier frequency of the segment varies at a rate of, at least, 1 giga-Hertz per second.

Abstract: An OVNA system employing an array of reference delays to estimate distance-variant phase distortion in probe light during an optical-frequency sweep thereof. The estimated distance-variant phase distortion is then used to perform a phase correction for the digital electrical signals generated in response to the probe light being passed through a device under test (DUT) during the same optical-frequency sweep. Advantageously, the performed phase correction enables the OVNA system to provide a more-accurate determination of certain optical characteristics of the DUT than that achievable without such phase correction.

Abstract: Various example embodiments for a wavelength selective switch including a direct grating interface are presented. In at least some example embodiments, a wavelength selective switch may include a light propagating element having a tilted fiber grating integrated therein, thereby providing a direct grating interface to the light propagating element. It is noted that use of such a direct grating interface may obviate the need for use of various components typically utilized within wavelength selective switches (e.g., front-end optics in the port direction, front-end optics and diffractive gratings in the wavelength direction, and so forth), thereby enabling the size of wavelength selective switches to be reduced or even for the wavelength selective switches to be made compact or even ultra-compact.

Abstract: An OVNA system employing an array of reference delays to estimate distance-variant phase distortion in probe light during an optical-frequency sweep thereof. The estimated distance-variant phase distortion is then used to perform a phase correction for the digital electrical signals generated in response to the probe light being passed through a device under test (DUT) during the same optical-frequency sweep. Advantageously, the performed phase correction enables the OVNA system to provide a more-accurate determination of certain optical characteristics of the DUT than that achievable without such phase correction.

Abstract: A WSS device in which a VIPA is used as a spectral disperser. In an example embodiment, the VIPA is configured to produce two or more diffraction orders on the LCOS micro-display of the WSS device. The LCOS micro-display is configurable to independently process light corresponding to different diffraction orders. For example, the LCOS micro-display may be used to implement: (i) optical-signal switching by applying different relative phase shifts to light of different diffraction orders to cause constructive interference at a selected one of the optical ports of the WSS device; (ii) optical-signal splitting by steering light of different diffraction orders to at least two different selected optical ports of the WSS device; and (iii) controllable optical-signal attenuation by applying different relative phase shifts to different diffraction orders to control the relative degree of constructive and destructive interference at a selected one of the optical ports of the WSS device.

Abstract: An optical imaging system capable of performing holographic imaging through a multimode optical fiber. Images of an object acquired by the system using different object-illumination conditions can advantageously be used to obtain a holographic image with reduced speckle contrast therein. Additionally, a beat-frequency map of the object acquired by the system using optical-reflectometry measurements therein can be used to augment the depth information of the holographic image for more-detailed three-dimensional rendering of the object for the user. Digital back-propagation techniques may be applied to reduce blurring in the holographic image and in the depth information caused, e.g., by modal dispersion and mode mixing in the multimode optical fiber. Some embodiments may also provide the capability for polarization-sensitive holographic imaging in different spectral regions of light.

Abstract: An apparatus includes a direct-detection optical data receiver to receive a data-modulated optical carrier. The direct-detection optical data receiver includes an optical power splitter, an array of at least three optical intensity detectors, and a digital signal processor. The digital signal processor is connected to receive digital values of intensity measurements of each of the optical intensity detectors of the array and to recover data of the received data-modulated optical signal from the digital values of the intensity measurements. The first optical intensity detector is connected to receive light from the optical power splitter via a dispersive optical path and the remaining of the optical intensity detectors of the array are connected to receive light from the optical power splitter via a multiple input and multiple output passive optical processing unit. The passive optical processing unit is configured to optically mix light received on different optical inputs thereof.

Abstract: An optical frequency-domain reflectometer (OFDR) capable of estimating the transfer matrix of a multimode optical fiber using mode-selective measurements performed from a single end of the fiber. In an example embodiment, the multimode optical fiber includes distributed reflectors designed to generate relatively strong light reflections along the length of the fiber at a desired spatial resolution. The embodiments may employ a signal-processing algorithm to estimate the fiber's transfer matrix by estimating segment transfer matrices corresponding to the fiber segments located between different ones of the distributed reflectors. Different embodiments of the disclosed OFDR can beneficially be adapted for use in different applications, such as fiber-optic component and module characterization, distributed optical sensing, biomedical imaging, OCT, etc.

Abstract: An apparatus includes an optical data receiver to receive a phase-modulated optical signal and to demodulate data therefrom. The optical data receiver includes an optical power splitter, first and second optical intensity detectors, and a digital signal processor. The digital signal processor is connected to receive digital values of intensity measurements of each of the optical intensity detectors. The first optical intensity detector is connected to receive light from the optical power splitter via a first optical path, and the second optical intensity detector is connected to receive light from the optical power splitter via a second optical path. The first and second optical paths have channel functions with different frequency dependencies.

Abstract: An optical frequency-domain reflectometer (OFDR) capable of estimating the transfer matrix of a multimode optical fiber using mode-selective measurements performed from a single end of the fiber. In an example embodiment, the multimode optical fiber includes distributed reflectors designed to generate relatively strong light reflections along the length of the fiber at a desired spatial resolution. The embodiments may employ a signal-processing algorithm to estimate the fiber's transfer matrix by estimating segment transfer matrices corresponding to the fiber segments located between different ones of the distributed reflectors. Different embodiments of the disclosed OFDR can beneficially be adapted for use in different applications, such as fiber-optic component and module characterization, distributed optical sensing, biomedical imaging, OCT, etc.

Abstract: An apparatus includes an optical data transmitter comprising an optical source of temporally incoherent light, an optical power splitter, an optical mode multiplexer, and a plurality of optical paths. The optical power splitter has an optical input and a plurality of optical outputs. The optical input is connected to receive the temporally incoherent light from the source. The optical mode multiplexer has a plurality of optical inputs and an optical output for connecting to a near end of an all-optical transmission fiber line. Each optical path connects a corresponding one of the optical outputs of the optical power splitter to a corresponding one of the optical inputs of the optical mode multiplexer. One or more of the optical paths of the plurality has or have an optical data modulator. A remaining one of the optical paths of the plurality is configured to transmit reference light from the optical power splitter to optical mode multiplexer.

Abstract: Various embodiments relate to a method including: coupling one or more optical spatial pilot signals into a first end of optical fiber, wherein the optical fiber is a multimode optical fiber; Reflecting and modifying each mode of the optical pilot signals at a second end of the optical fiber; receiving a reflected portion of the one or more optical spatial pilot signals at the first end of the of the optical fiber in response to the reflected portion having propagated through the optical fiber in both directions; processing the reflected spatial pilot to determine components of one of a round-trip transfer matrix of the optical fiber and a single-direction transfer matrix of the optical fiber.

Abstract: An apparatus includes an optical data transmitter comprising an optical source of temporally incoherent light, an optical power splitter, an optical mode multiplexer, and a plurality of optical paths. The optical power splitter has an optical input and a plurality of optical outputs. The optical input is connected to receive the temporally incoherent light from the source. The optical mode multiplexer has a plurality of optical inputs and an optical output for connecting to a near end of an all-optical transmission fiber line. Each optical path connects a corresponding one of the optical outputs of the optical power splitter to a corresponding one of the optical inputs of the optical mode multiplexer. One or more of the optical paths of the plurality has or have an optical data modulator.

Abstract: Various embodiments relate to a method including: coupling one or more optical spatial pilot signals into a first end of optical fiber, wherein the optical fiber is a multimode optical fiber; Reflecting and modifying each mode of the optical pilot signals at a second end of the optical fiber; receiving a reflected portion of the one or more optical spatial pilot signals at the first end of the of the optical fiber in response to the reflected portion having propagated through the optical fiber in both directions; processing the reflected spatial pilot to determine components of one of a round-trip transfer matrix of the optical fiber and a single-direction transfer matrix of the optical fiber.

Abstract: An apparatus, including: an optical sensor fiber having a first end optically couplable to receive light from a light source, wherein the optical sensor fiber is a multimode optical fiber configured to carry light in different spatial propagating modes, wherein the optical sensor fiber is constructed such that environmental fluctuations couple light energy between some of the spatial propagating modes; a spatial propagating mode demultiplexer optically coupled to a second end the optical sensor fiber and configured to separate a plurality of light signals received from different ones of the spatial propagating modes; and an optical receiver configured to process the separated light signals and to estimate a longitudinal position of one of the environmental fluctuations along the optical sensor fiber based a measured delay between arrival times of the separated light signals.

Abstract: We disclose a vertical-cavity surface-emitting laser (VCSEL) whose optical resonator can support multiple transverse resonator modes. The VCSEL has a plurality of electrodes that can apply individually controllable electrical currents to the active semiconductor region of the optical resonator and be configured to excite, e.g., a single selected transverse resonator mode or a desired linear combination of transverse resonator modes. In some embodiments, the VCSEL's optical resonator may have an effective lateral geometric shape that causes the excitable transverse resonator modes to correspond to the waveguide modes of a cylindrical optical fiber.

Abstract: An apparatus includes a plurality of VCSELs, a master laser, one or more electrical drivers, and an optical combiner. The master laser is configured to transmit laser light to the VCSELs to optically lock wavelengths of the VCSELs. The one or more electrical drivers are connected to directly electrically modulate the VCSELs in a manner responsive to one or more digital data stream. The optical combiner is configured to combine light received from, at least, a pair of the VCSELs into an optical carrier with a substantially phase digital data modulation.

Abstract: We disclose a vertical-cavity surface-emitting laser (VCSEL) whose optical resonator can support multiple transverse resonator modes. The VCSEL has a plurality of electrodes that can apply individually controllable electrical currents to the active semiconductor region of the optical resonator and be configured to excite, e.g., a single selected transverse resonator mode or a desired linear combination of transverse resonator modes. In some embodiments, the VCSEL's optical resonator may have an effective lateral geometric shape that causes the excitable transverse resonator modes to correspond to the waveguide modes of a cylindrical optical fiber.