Abstract: A free-space optical communication method is provided. The method includes generating, at a transmitter of a satellite, an optical frequency comb and a pump signal, modulating the optical frequency comb to generate a data signal and an idler signal that is a phase conjugate of the data signal, attenuating the pump signal, transmitting over free-space, from the satellite, a communication signal having the data signal, the idler signal and the pump signal, receiving from the satellite, at a receiver, the transmitted communication signal having the data signal, the idler signal, and the attenuated pump signal, amplifying, at a phase-sensitive amplifier, the data signal and the idler signal, and demodulating the data signal and the idler signal to extract data.

Abstract: An integrated pluggable optical tap module configured to be coupled to a host interface of a network equipment for tapping a signal of an optical transport link comprises a first, a second optical interface, and an active optical receiver. The optical pluggable module also includes a passive optical tap for splitting a signal received from the first optical interface and transmitting the signal on the second optical interface and a copy of the signal to the active optical receiver. The active optical receiver converts said signal to an electrical signal for transmission to the host interface.

Abstract: A system and method for applying a time-varying phase shift to an optical signal is described. Such a phase shift results in a frequency shift of the optical signal, which can be useful for instance in sensing applications. The design uses cross phase modulation (XPM) in a nonlinear medium such as optical fiber. The pump producing the XPM experiences a change in energy along the medium, for instance due to loss. The pump and signal have mismatched group velocities such that they walk-off each other in time, and the pump pulse repetition rate is chosen so that it has a specific relationship with respect to the walk-off. The design is compatible with very low signal loss and does not require high fidelity electrical control signals. It is capable of high-efficiency one-directional serrodyne frequency shifts, as well as producing symmetric frequency shifts. It can also be made polarization independent.

Abstract: A polarization recovery device comprises an input that receives a first optical signal with unknown polarization and with at least one signal parameter at an initial value, a first output that outputs a second optical signal with known polarization and with the at least one signal parameter at or near the initial value, and a recovery block that generates the second optical signal based on the first optical signal.

Abstract: The disclosure relates to a method, an optical receiver and an optical system for compensating, at an optical receiver, signal distortions induced in an optical carrier signal by a periodic copropagating optical signal, wherein the optical carrier signal and the copropagating signal copropagate at least in part of an optical system or network, by: receiving, at the optical receiver, the optical carrier signal, wherein the optical carrier signal is distorted by the copropagating signal; determining, at the optical receiver, a period of a periodic component of the distorted optical carrier signal; determining, at the optical receiver, a periodic distortion of the distorted optical carrier signal; and generating a compensation signal to correct the distorted optical carrier signal according to the determined periodic distortion.

Abstract: An underwater communications system may include a first device and a second device being movable relative to one another. The first device may include a first laser transmitter configured to generate a first laser beam having a selectable spatiotemporal beam shape from among a plurality thereof, and a first controller coupled to the first laser transmitter and configured to select a spatiotemporal beam shape for the first laser beam from among the spatiotemporal beam shapes. The second device may include a second laser receiver configured to receive the first laser beam, and a second controller coupled to the second laser receiver.

Abstract: A system for correcting phase noise and/or drift, the system includes an optical signal module being capable of amplitude modulating the optical signal while being phase- and/or frequency-shifted. Further, the system includes a beam splitter capable of separating at least backward travelling waves based on polarization. Moreover, a fiber connected to the beam splitter and a polarization rotator capable of changing the polarization of the optical signal are provided. The system has a partially reflecting reflector capable of creating a backward travelling wave as well as a photodiode capable of receiving the backward travelling wave. The photodiode is capable of generating a detection signal used for detecting phase noise and/or drift in the backward travelling wave.

Abstract: In an example embodiment, an optical communication system includes an implantable optical transmitter and an external optical receiver. The transmitter includes a housing having one or more drivers, plural light emitting sources, and an optical element arranged therein. Each driver converts a digital data signal into modulation signals to drive the sources. Each source generates a light beam in response to a corresponding modulation signal, each light beam contributing to form a single optical signal. The optical element directs the light beams to exit the housing such that a peak position of light intensity of each light beam is separated from a corresponding peak position of light intensity of an adjacent light beam by at least a first distance and less than a second distance. The optical receiver includes at least one photodiode that detects light generated by the sources and generates a reconstructed data signal.

Abstract: Aspects of the technology include establishing a primary communication link between a communication system of a first balloon and a communication system of a second balloon, detecting a movement of the second balloon relative to the first balloon that is expected to cause the primary communication link to become unavailable at a given time during the movement, establishing an RF communication link between an RF communication system of the first balloon and an RF communication system of the second balloon, detecting that the movement of the second balloon relative to the first balloon is such that the primary communication link between the communication system of the first balloon and the optical communication system of the second balloon can be re-established, and re-establishing the primary communication link between the communication system of the first balloon and the communication system of the second balloon.

Abstract: An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.

Abstract: An object is to provide an optical transmission apparatus in which dummy lights can be arranged according to an arrangement of optical signals. A plurality of optical signals of different frequencies arranged in a frequency grid are input to a multiplexing unit and the multiplexing unit multiplexes the input optical signals. A dummy light output unit identifies a dummy light to be arranged in the frequency grid based on the plurality of optical signals and outputs the dummy light. A multiplexing unit multiplexes an optical signal multiplexed by the multiplexing unit and the dummy light output from the dummy light output unit to output a wavelength-multiplexed optical signal L.

Abstract: Part of compensation of the transmission characteristics of the optical transmitter is performed by transmitter compensation circuitry disposed at a stage prior to the optical transmitter. Remaining part of compensation of the transmission characteristics of the optical transmitter and compensation of the transmission characteristics of the optical receiver is performed by a receiver compensation circuitry disposed at a stage subsequent to the optical receiver. Transmitter compensation characteristics of the transmitter compensation circuitry is set so that a peak-to-average-power ratio of an output signal from the transmitter compensation circuitry becomes equal to or smaller than a predetermined value.

Abstract: An inventive rotatable optical short-range transceiver has: a support which is rotatable around a rotation axis, an optical receiver which is arranged at the support on the rotation axis to receive an optical reception signal from a first direction, an optical transmitter which is arranged at the support to be adjacent to the optical receiver to emit an optical transmission signal in a second direction, and an optical transmission/reception unit which is configured to allow interruption-free rotatable optical data communication, wherein the optical transmission/reception unit is arranged at the support above the optical receiver and extends over the optical receiver and the optical transmitter, and wherein the optical transmission/reception unit has a support structure for mounting at the support, which is implemented integrally with the optical transmission/reception unit.

Abstract: Deep neural networks (DNNs) have become very popular in many areas, especially classification and prediction. However, as the number of neurons in the DNN increases to solve more complex problems, the DNN becomes limited by the latency and power consumption of existing hardware. A scalable, ultra-low latency photonic tensor processor can compute DNN layer outputs in a single shot. The processor includes free-space optics that perform passive optical copying and distribution of an input vector and integrated optoelectronics that implement passive weighting and the nonlinearity. An example of this processor classified the MNIST handwritten digit dataset (with an accuracy of 94%, which is close to the 96% ground truth accuracy). The processor can be scaled to perform near-exascale computing before hitting its fundamental throughput limit, which is set by the maximum optical bandwidth before significant loss of classification accuracy (determined experimentally).

Abstract: A method and system are provided for continuously monitoring bandwidth utilization in real time on a backbone of a network. Prefixes using the highest traffic can be identified and additional bandwidth can be provisioned in the form of optical transponder wavelengths. The additional bandwidth can be an express path that passes directly through optical nodes (thereby bypassing transit network devices) to the destination optical node. A centralized controller can perform the monitoring of the network devices, decide that an express path needs to be generated, and control both the network device and the optical network nodes to generate the express path from the network device, through the optical network, to the destination network device. The controller can apply and remove IP static routes and IP addresses associated with an express path. Additionally, the controller can request the setup or tear-down of an optical wavelength within the optical network.

Abstract: A method for automatic power and modulation management in a communication network includes (1) generating a management function of (a) mutual information per symbol (MIPS) of the communication network and (b) output power (P) of a transmitter of the communication network, determining a selected MIPS value and a selected P value which achieve a maximum value of the management function, and causing the transmitter of the communication network to operate according to the selected MIPS value and the selected P value.

Abstract: The present invention proposes a new method for solving the problem of fault tolerance. This new approach obtains all secondary routes assigned to each possible connection (user). The secondary routes replace the main routes when these are affected by at least one fault, which keeps the users connected as long as, for each connection, there is at least one route with operative links for reaching the destination nodes thereof. This new approach solves the general case of an arbitrary set of simultaneous link failures. The method also assesses the number of wavelengths for each link of the network, so that the probability of any connection request from a determined user c being blocked is less than a predefined threshold ?c, despite the possible occurrence of the fault scenario.

Abstract: A distributed antenna system comprises: one or more access units configured to receive multiple downlink radio frequency signal sets, and further configured to convert the multiple downlink radio frequency signal sets into multiple downlink optical signal sets; a first wavelength division multiplexing unit configured to multiplex the multiple downlink optical signal sets to generate a first wavelength division multiplexing optical signals; a first wavelength division demultiplexing unit configured to demultiplex the first wavelength division multiplexing optical signals to obtain the multiple downlink optical signal sets; a first optical fiber, coupled between the first wavelength division multiplexing unit and the first wavelength division demultiplexing unit, and configured to transmit the first wavelength division multiplexing optical signal; and multiple first remote units coupled to the first wavelength division multiplexing unit, and configured to convert the multiple downlink optical signal sets into t

Abstract: A system and method for analog estimation of a spectral correlation function (SCF) provides a photonic carrier to generate a signal comb and offset comb, each comprising N comb tones separated by respective repetition rates ?F and ?F+?F. The signal and offset combs are amplitude-modulated according to an inbound RF signal of interest and filtered via periodic optical filters to produce a sequence of N Fourier components of the signal comb and N Fourier components of the offset comb, each filtered signal comb component overlapping with a filtered offset comb component. In-phase/quadrature (I/Q) components of the products of each component of the complex conjugate of the filtered offset comb and the overlapping counterpart of the filtered signal comb are generated in an optical receiver and digitized into slices of the SCF at a fixed time instance and center frequency, correlated at various cyclic separations ?.

Abstract: A smart light source configured for visible light communication. The light source includes a controller comprising a modem configured to receive a data signal and generate a driving current and a modulation signal based on the data signal. Additionally, the light source includes a light emitter configured as a pump-light device to receive the driving current for producing a directional electromagnetic radiation with a first peak wavelength in the ultra-violet or blue wavelength regime modulated to carry the data signal using the modulation signal. Further, the light source includes a pathway configured to direct the directional electromagnetic radiation and a wavelength converter optically coupled to the pathway to receive the directional electromagnetic radiation and to output a white-color spectrum. Furthermore, the light source includes a beam shaper configured to direct the white-color spectrum for illuminating a target of interest and transmitting the data signal.