Abstract: An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

Abstract: An optical full-field transmitter (OFFT) includes a plurality of optical circulators and a polarization beam combiner. The plurality of optical circulators are fabricated on a silicon-on-insulator (SOI) substrate, where each of the optical circulators has (a) a first port that optically couples to a high-quality optical source, (b) a second port that optically couples to a child laser configured to receive amplitude modulation data, and (c) a third port optically coupled to a phase modulator that (i) is configured to receive a phase modulation data and (ii) includes an output port that outputs amplitude and phase modulated light. The polarization beam combiner receives the amplitude and phase modulated light from each of the optical circulators and outputs combined amplitude and phase modulated light.

Abstract: A beam steering subsystem is provided in an optical communication system. The beam steering subsystem is configured for steering a free-space optical (FSO) beam from a first transceiver to a second transceiver disposed remotely from the first receiver. The beam steering subsystem includes a beam steering device disposed between the first transceiver and the second transceiver, and an optical tracking unit in optical communication and electrical communication with the beam steering device. The wherein the beam steering device is further configured to (i) receive the FSO beam from the first transceiver, (ii) receive an optical tracking signal from the second transceiver, (iii) optically relay the received optical tracking signal to the optical tracking unit, and (iv) steer the FSO beam to the second transceiver based on an electrical feedback control signal from optical tracking unit.

Abstract: A method for tuning a power characteristic of an optical frequency comb includes controlling a modulating light source according to a plurality of modulation parameters to generate an optical frequency comb including a plurality of optical tones. Additionally, at least one of the plurality of modulation parameters is changed until a total power of the plurality of optical tones is greater than or equal to a minimum threshold value. Furthermore, at least one of the plurality of modulation parameters are changed until respective powers of each of the plurality of optical tones are within a predetermined proximity to respective target powers of each of the plurality of optical tones.

Abstract: A coherent passive optical network includes a downstream transceiver and first and second upstream transceivers in communication with an optical transport medium. The downstream transceiver includes a downstream processor for mapping a downstream data stream to a plurality of sub-bands, and a downstream transmitter for transmitting a downstream optical signal modulated with the plurality of sub-bands. The first upstream transceiver includes a first local oscillator (LO) for tuning a first LO center frequency to a first sub-band of the plurality of sub-bands, and a first downstream receiver for coherently detecting the downstream optical signal within the first sub-band. The second upstream transceiver includes a second downstream receiver configured for coherently detecting the downstream optical signal within a second sub-band of the plurality of sub-bands. The downstream processor dynamically allocates the first and second sub-bands to the first and second transceivers in the time and frequency domains.

Abstract: An optical communication network includes a downstream optical transceiver. The downstream optical transceiver includes at least one coherent optical transmitter configured to transmit a downstream coherent dual-band optical signal having a left-side band portion, a right-side band portion, and a central optical carrier disposed within a guard band between the left-side band portion and the right-side band portion. The network further includes an optical transport medium configured to carry the downstream coherent dual-band optical signal from the downstream optical transceiver. The network further includes at least one modem device operably coupled to the optical transport medium and configured to receive the downstream coherent dual-band optical signal from the optical transport medium. The at least one modem device includes a downstream coherent optical receiver, and a first slave laser injection locked to a frequency of the central optical carrier.

Abstract: An edge wavelength-switching system includes an optical switch and a wavelength selective switch. The optical switch includes a west hub-side port, an east hub-side port, a west local-side port, and an east local-side port. The wavelength selective switch includes (i) a multiplexed port optically coupled to the west local-side port and (ii) a bypass port optically coupled to the east local-side port, and (iii) a plurality of demultiplexed ports. An optical network includes a network hub including an M-by-N1 wavelength-selective switch, N1>M?1, a first network node, and a second network node. Each of the first and second network nodes includes a respective edge wavelength-switching system. The network hub, the first network node, and the second network node are optically coupled.

Abstract: Coherent phase recovery method includes producing, with a transmit-side frequency-comb source, a first frequency-comb signal that includes a pilot tone and a first optical tone having a first center wavelength that differs from a pilot center wavelength of the pilot tone. The method also includes coherently modulating the first optical tone to yield a first modulated signal; and generating a second frequency-comb signal with a receive-side frequency-comb source driven by the pilot tone. The method also includes extracting, from the second frequency-comb signal, a first local-oscillator tone having the first center wavelength; and demodulating the first modulated signal by homodyning the first modulated signal with the first local-oscillator tone.

Abstract: A method for phase compensation in an optical communication network includes (1) modifying a modulated signal according to one or more correction factors to generate a compensated signal, to compensate for phase rotation, (2) modulating a magnitude of an optical signal in response to a magnitude of the compensated signal, and (3) modulating a phase of the optical signal, after modulating the magnitude of the optical signal, in response to a phase of the compensated signal.

Abstract: A full duplex communication network includes an optical transmitter end having a first coherent optics transceiver, an optical receiver end having a second coherent optics transceiver, and an optical transport medium operably coupling the first coherent optics transceiver to the second coherent optics transceiver. The first coherent optics transceiver is configured to simultaneously transmit a downstream optical signal and receive an upstream optical signal. The second coherent optics transceiver is configured to simultaneously receive the downstream optical signal from the first coherent optics transceiver and transmit the upstream optical signal first coherent optics transceiver. At least one of the downstream optical signal and the upstream optical signal includes at least one coherent optical carrier and at least one non-coherent optical carrier.

Abstract: An injection locking laser source is provided for an optical communications system. The injection locking laser source includes a laser cavity configured to receive an externally injected low linewidth primary light source. The laser cavity includes a cavity length, a cavity facet reflectivity, and a cavity quality factor. The injection locking laser source further includes an emitting region configured to output a secondary light source injection locked to the externally injected low linewidth primary light source at a stable detuning frequency based on a photon number, a steady-state phase, and a carrier number of the primary light source injected into the cavity.

Abstract: A coherent passive optical network includes a downstream transceiver and first and second upstream transceivers in communication with an optical transport medium. The downstream transceiver includes a downstream processor for mapping a downstream data stream to a plurality of sub-bands, and a downstream transmitter for transmitting a downstream optical signal modulated with the plurality of sub-bands. The first upstream transceiver includes a first local oscillator (LO) for tuning a first LO center frequency to a first sub-band of the plurality of sub-bands, and a first downstream receiver for coherently detecting the downstream optical signal within the first sub-band. The second upstream transceiver includes a second downstream receiver configured for coherently detecting the downstream optical signal within a second sub-band of the plurality of sub-bands. The downstream processor dynamically allocates the first and second sub-bands to the first and second transceivers in the time and frequency domains.

Abstract: A skew compensation system for a coherent optical communication network includes a transmitter and a receiver in operable communication with an optical transport medium of a coherent optical network. The transmitter includes a first transmitter-side tunable delay line configured to delay transmission of a first signal by a first skew amount, thereby producing a pre-compensated first signal. The receiver includes a first receiver-side tunable delay line configured to delay transmission of the pre-compensated first signal to a digital signal processor (DSP) of the receiver by a second skew amount, thereby producing a final signal that is both pre-compensated and post-compensated (i.e., fully compensated).

Abstract: An optical full-field transmitter for an optical communications network includes a primary laser source configured to provide a narrow spectral linewidth for a primary laser signal, and a first intensity modulator in communication with a first amplitude data source. The first intensity modulator is configured to output a first amplitude-modulated optical signal from the laser signal. The transmitter further includes a first phase modulator in communication with a first phase data source and the first amplitude-modulated optical signal. The first phase modulator is configured to output a first two-stage full-field optical signal. The primary laser source has a structure based on a III-V compound semiconductor.

Abstract: A method for allocating bandwidth to a first ONU, a second ONU, M1 ONUs, and M2 ONUs includes, during an allocation cycle, (i) granting a respective upstream time slot to, of a plurality of N ONUs, only each of the M1 ONUs, and (ii) granting a first upstream time slot to the first ONU. Each of the M1 ONUs and M2 ONUs is one of the plurality of N ONUs. The method also includes, during a subsequent cycle, (i) granting a respective upstream time slot to, of the plurality of N ONUs, only each of the M2 ONUs. The N ONUs includes a skipped-ONU that is one of either, and not both, the M1 ONUs and the M2 ONUs. The method includes, during the subsequent allocation cycle, granting a second upstream time slot to a second ONU, which is not one of the plurality of N ONUs.

Abstract: A method for synchronizing a data frame and data symbols in a communication system includes generating a training sequence including a serial sequence of data symbols that are conjugate symmetric, inserting the training sequence in a transmitter-side data frame, converting constituent data symbols of the transmitter-side data frame to communication signals, transmitting the communication signals from a transmitter to a receiver, converting the communication signals to a stream of received data symbols, detecting presence of the training sequence in the stream of received data symbols, and identifying a position of a received data frame from the presence of the training sequence.

Abstract: A digital receiver is configured to process a polarization multiplexed carrier from a communication network. The polarization multiplexed carrier includes a first polarization and a second polarization. The receiver includes a first lane for transporting a first input signal of the first polarization, a second lane for transporting a second input signal of the second polarization, a dynamic phase noise estimation unit disposed within the first lane and configured to determine a phase noise estimate of the first input signal, a first carrier phase recovery portion configured to remove carrier phase noise from the first polarization based on a combination of the first input signal and a function of the determined phase noise estimate, and a second carrier phase recovery portion configured to remove carrier phase noise from the second polarization based on a combination of the second input signal and the function of the determined phase noise estimate.

Abstract: A method and apparatus of distortion compensation during data transmission uses an interweaved look-up table (ILUT) to mitigate residual signal distortions in a signal transmitted over a transmission link. The ILUT interweaves states across both an I and a Q tributary to calculate mean error and an extended symbol basis. As a result, the method works particularly well against two-dimensional distortions like nonlinearity, IQ-imbalance, and quadrature error. The method may be used for either pre-compensation when it is combined with k-means clustering in a transmitter or post-compensation when it is combined with maximum likelihood (ML) detection in a receiver.

Abstract: A full duplex communication network includes an optical transmitter end having a first coherent optics transceiver, an optical receiver end having a second coherent optics transceiver, and an optical transport medium operably coupling the first coherent optics transceiver to the second coherent optics transceiver. The first coherent optics transceiver is configured to (i) transmit a downstream optical signal at a first wavelength, and (ii) simultaneously receive an upstream optical signal at a second wavelength. The second coherent optics transceiver is configured to (i) receive the downstream optical signal, and (ii) simultaneously transmit the upstream optical signal. The first wavelength has a first center frequency separated from a second center frequency of the second wavelength.

Abstract: A communications network includes a central communication unit, an optical transport medium, and a plurality of remote radio base stations. The central communication unit generates, within a selected millimeter-wave frequency band, a plurality of adjacent two-tone optical frequency conjugate pairs. Each conjugate pair includes a first optical tone carrying a modulated data signal, and a second optical tone carrying a reference local oscillator signal. The optical transport medium transports the plurality of two-tone conjugate pairs to the plurality of radio base stations, and each base station receives at least one conjugate pair at an optical front end thereof. The optical front end separates the first optical tone from the second optical tone, and converts the first optical tone into a millimeter-wave radio frequency electrical signal.