A system for estimating an imbalance between electrical-optical responses of an in-phase (I) channel and a quadrature (Q) channel in an optical amplitude and phase modulator (optical IQ modulator) includes an optical detector (PD), an analog-digital converter (ADC), and an imbalance operation unit that estimates an imbalance between electrical-optical responses of an I channel and a Q channel in the optical IQ modulator, wherein the imbalance operation unit includes an input signal information receiving unit that receives information regarding a first modulation signal, and an intensity information receiving unit that receives intensity information of the digitalized output signal from the ADC, and the imbalance operation unit estimates an imbalance between electrical-optical responses of an I channel and a Q channel in the optical IQ modulator using information regarding a first modulation signal and intensity information of the digitalized output signal.

A highly integrated multi-channel optical module is provided. The optical module includes an optical source device mounted on a substrate by an optical source mount unit, a waveguide mounted on the substrate by a waveguide mount unit, a lens mount unit disposed between the optical source device and the waveguide and mounted on the substrate, and a lens unit fixed to the lens mount unit by an adhesive cured by ultraviolet (UV) parallel light, wherein a light path of the UV parallel light is formed in the lens mount unit by a reflector attached on a side surface of the lens mount unit, and the UV parallel light moves along the light path and cures the adhesive coated on an upper portion of the lens mount unit facing a lower end portion of the lens unit.

The proposed technology allows for 1+1 optical protection and may improve coherent module output optical power by 3 dB over similar transmitter (Tx) and receiver (Rx) implementation complexity, as well as allow for integration into existing datacenter formats.

A system and method generates confined electromagnetic radiation emanating from a remote position along a line of sight. The system includes a laser arrangement and a wavefront modifier. The laser arrangement generates at least one laser beam. The wavefront modifier produces a spatial arrangement of foci of the laser beam directed along the line of sight. The foci of the laser beam induce plasma filaments within an atmosphere at the remote position along the line of sight. The plasma filaments emit the electromagnetic radiation emanating from the remote position along the line of sight.

An optical transmitter includes quadrature modulators and light receiving elements to which inverted output light of output light from the quadrature modulators is input, the quadrature modulators including parent Mach-Zehnder modulators in respective paths of a first pair of paths into which carrier light from a light source is split, the parent Mach-Zehnder modulators including child Mach-Zehnder modulators including first phase modulation units, and second phase modulation units. When blocking a transmission optical signal, the voltage amplitude of a transmission electrical signal to be applied to the quadrature modulator is adjusted such that it is smaller than a half-wave voltage, at most two dither signals are applied to the first phase modulation units, a component output by the light receiving element, the component having n times a frequency of the dither signals, is detected, and bias voltages to be applied to the first phase modulation units are controlled such that the component having n times the frequency is minimized.

An optical transmitter has an optical modulator having Mach-Zehnder interferometers, modulator drivers configured to drive the optical modulator by a drive signal, a low frequency generator configured to generated a low frequency signal that changes a ratio of a driving amplitude with respect to a half-wave voltage of the optical modulator, a photodetector configured to detect a portion of output light of the optical modulator, a detector configured to detect a low frequency component contained in a detected signal from the photodetector using the low frequency signal, and a bias voltage controller configured to control a bias voltage for the optical modulator such that the detected low frequency component becomes the maximum and in-phase with the superimposed low frequency signal.

An optical transmitter includes an optical modulator that is driven by a driving signal, an acquisition part, and a controller. The acquisition part obtains a relationship between a fluctuation of a parameter to adjust the driving signal and a fluctuation of a state of output light from the optical modulator due to the fluctuation of the parameter. The controller controls an amplitude of the driving signal on the basis of the obtained relationship.

Methods and apparatus for providing spectrally beam-combined fiber-based transmitters and/or receivers for laser communications, LiDAR, and similar devices. A transmitter can include a launch array configured to spatially position each output beam of pulsed lasers, a transform optical component to correct deflection of the output beams of the pulsed lasers from the launch array, and a dispersive optical element to combine beams from the transform optical element and generate a spectrally combined beam. A receiver can include spectral comb filters to spectrally discriminate multi-wavelength detected signals from background illumination.

At a controller of an optical module including optical transmitters and optical receivers coupled to the controller and coupled to first and second optical fibers: responsive to a first command, first configuring the optical module to operate in a normal mode in which the optical module operates at a maximum communication capacity by transmitting and receiving a maximum number of wavelengths, that the optical module is capable of transmitting and receiving, on each of the first optical fiber and the second optical fiber; and responsive to a second command, second configuring the optical module to operate in a backward compatible legacy mode in which the optical module operates at a reduced communication capacity compatible with a legacy optical module by transmitting and receiving a reduced number of wavelengths, that is less than the maximum number of wavelengths, on each of the first optical fiber and the second optical fiber.

An example apparatus includes a mode selective detector, a measurement module, a difference calculator and a threshold and alarm module. The mode selective detector detects a plurality of modes of a spatially multiplexed signal. The measurement module measures a parameter for the plurality of modes of the spatially multiplexed signal, wherein the parameter is a power or a signal to noise ratio (SNR). The difference calculator compares the measured parameter among a subset modes and/or among a known set of unperturbed parameters and determines a differential, the subset including at least one mode. The threshold and alarm module sets an alarm indicator when the differential is out of bounds.