Abstract: Various example embodiments for supporting optical transport systems are presented. Various example embodiments for supporting optical transport systems may be configured to support optical transport systems that support multiple fibers based on use of spatial division multiplexing (SDM) techniques. Various example embodiments for supporting optical transport systems that support multiple fibers based on use of SDM techniques may be configured to support optical transport systems that support multiple fibers based on use of an anylane add/drop capability that is based on use of a Clos architecture (e.g., a spatially-switched distributed Clos architecture with a single stage of switching for network traffic that passes through the node, a spatially-switched distributed Clos architecture with two stages of switching for network traffic that passes through the node, a spatially-switched node-contained Clos architecture with three stages of switching for network traffic that passes through the node, or the like).

Abstract: An apparatus includes an optical PSK transmitter configured to output carrier-suppressed optical signal phase-modulated according to a M-PSK constellation without substantial amplitude modulation. The apparatus includes an optical phase modulator, a driver configured to drive the modulator with a PAM-N electrical signal, N>M, and a signal encoder configured to map an input bit stream to the PAM-N electrical signal.

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 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: An optical data receiver includes optical hybrids, light detectors and a digital signal processor. Each optical hybrid outputs mixtures of a corresponding one of the polarization components of a received data-modulated optical carrier with reference light. Each light detector outputs digital measurements of the mixtures from a corresponding one of the optical hybrids. The digital signal processor identifies data symbols of a constellation having parts transmitted on both polarization components of the data-modulated optical carrier responsive to receipt of the digital measurements. The transmitted data-modulated optical carrier has about a same total light intensity in each modulation time slot thereof. Each data symbol is defined by in-phase and quadrature-phase electric field coordinates of both polarization components. Pairs of in-phase and quadrature-phase electric coordinates of each of the polarization components are on a preselected set of one or more concentric circles about an origin.

Abstract: An apparatus includes a multi-mode optical fiber having a selected plurality of optical propagating modes. The selected plurality may include only a proper subset of or may include all of the optical propagating modes of the multi-mode optical fiber. Each optical propagating mode of the selected plurality has a group velocity that varies over a corresponding range for light in, at least, one of the optical telecommunications C-band, the optical telecommunications L-band, and the optical telecommunications S-band. The ranges corresponding to different ones of the modes of the selected plurality are non-overlapping. The ranges of a group velocity-adjacent pair of the ranges are separated by a nonzero gap of less than about 10,000 meters per second.

Abstract: An apparatus includes a multi-mode optical fiber having a selected plurality of optical propagating modes. The selected plurality may include only a proper subset of or may include all of the optical propagating modes of the multi-mode optical fiber. Each optical propagating mode of the selected plurality has a group velocity that varies over a corresponding range for light in, at least, one of the optical telecommunications C-band, the optical telecommunications L-band, and the optical telecommunications S-band. The ranges corresponding to different ones of the modes of the selected plurality are non-overlapping. The ranges of a group velocity-adjacent pair of the ranges are separated by a nonzero gap of less than about 10,000 meters per second.

Abstract: An apparatus includes a multi-mode optical fiber having a selected plurality of optical propagating modes. The selected plurality may include only a proper subset of or may include all of the optical propagating modes of the multi-mode optical fiber. Each optical propagating mode of the selected plurality has a group velocity that varies over a corresponding range for light in, at least, one of the optical telecommunications C-band, the optical telecommunications L-band, and the optical telecommunications S-band. The ranges corresponding to different ones of the modes of the selected plurality are non-overlapping. The ranges of a group velocity-adjacent pair of the ranges are separated by a nonzero gap of less than about 10,000 meters per second.

Abstract: An optical data receiver includes optical hybrids, light detectors and a digital signal processor. Each optical hybrid outputs mixtures of a corresponding one of the polarization components of a received data-modulated optical carrier with reference light. Each light detector outputs digital measurements of the mixtures from a corresponding one of the optical hybrids. The digital signal processor identifies data symbols of a constellation having parts transmitted on both polarization components of the data-modulated optical carrier responsive to receipt of the digital measurements. The transmitted data-modulated optical carrier has about a same total light intensity in each modulation time slot thereof. Each data symbol is defined by in-phase and quadrature-phase electric field coordinates of both polarization components. Pairs of in-phase and quadrature-phase electric coordinates of each of the polarization components are on a preselected set of one or more concentric circles about an origin.

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 optical line card includes a plurality of coherent receivers and a plurality of optical modulators. The coherent receivers are each configured to receive a corresponding channel of a received optical superchannel. The optical modulators are each configured transmit a corresponding channel of a transmitted optical superchannel. Each of a plurality of optical splitters is configured to receive a corresponding one of a plurality of unmodulated optical signals from an optical source external to the line card. Each splitter directs a first portion of light received by that splitter to a corresponding one of the coherent receivers, and a second portion of light received by that splitter to a corresponding one of said optical modulators.

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: An apparatus includes a multi-mode optical fiber having a selected plurality of optical propagating modes. The selected plurality may include only a proper subset of or may include all of the optical propagating modes of the multi-mode optical fiber. Each optical propagating mode of the selected plurality has a group velocity that varies over a corresponding range for light in, at least, one of the optical telecommunications C-band, the optical telecommunications L-band, and the optical telecommunications S-band. The ranges corresponding to different ones of the modes of the selected plurality are non-overlapping. The ranges of a group velocity-adjacent pair of the ranges are separated by a nonzero gap of less than about 10,000 meters per second.

Abstract: An apparatus includes a multi-mode optical fiber having a selected plurality of optical propagating modes. The selected plurality may include only a proper subset of or may include all of the optical propagating modes of the multi-mode optical fiber. Each optical propagating mode of the selected plurality has a group velocity that varies over a corresponding range for light in, at least, one of the optical telecommunications C-band, the optical telecommunications L-band, and the optical telecommunications S-band. The ranges corresponding to different ones of the modes of the selected plurality are non-overlapping. The ranges of a group velocity-adjacent pair of the ranges are separated by a nonzero gap of less than about 10,000 meters per second.

Abstract: An optical apparatus includes a front optics section and a spectrometer section. The front optics section includes a spot de-multiplexer configured to receive a plurality of multi-mode optical signals each having a plurality of modal components, and to output in a linear array of a corresponding plurality of optical beams for each multimode optical signal. The spectrometer section includes a wavelength steering element configured to separate each of the optical beams into a plurality of wavelength channels. A fiber steering element is configured to steer the wavelength channels between the optical beams.

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.