A receiver system is provided for receiving a coherent Pulse Amplitude Modulation (PAM) encoded signal. The receiver system may include an optical polarization component configured to modulate a polarization of the received coherent PAM encoded signal. The receiver system may further include a digital signal processor (DSP) configured to perform polarization recovery between the received coherent PAM encoded signal and the LO signal using a first control loop, and to perform phase recovery between the received coherent PAM encoded signal and the LO signal using a second control loop.

Embodiments of the present disclosure are directed toward techniques and apparatus comprising at least one layer of an ONN that includes an optical matrix multiplier provided in a semiconductor substrate to receive a plurality of optical signal inputs and to linearly transform the plurality of optical signal inputs into a plurality of optical signal outputs. The optical matrix multiplier comprises one or more 22 unitary optical matrices optically interconnected to implement a singular value decomposition (SVD) of a matrix, and a nonlinear optical device coupled with the optical matrix multiplier in the semiconductor substrate, to receive the optical signal outputs and to provide an optical output that is generated in a nonlinear manner in response to the optical signal outputs of the optical matrix multiplier reaching saturation or attenuation. Additional embodiments may be described and claimed.

A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

A method and structure for signal propagation in a coherent optical receiver device. Asynchronous equalization helps to reduce complexity and power dissipation, and also improves the robustness of timing recovery. However, conventional devices using inverse interpolation filters ignore adaptation algorithms. The present invention provides for forward propagation and backward propagation. In the forward case, the filter input signal is forward propagated through a filter to the adaptation engine, while, in the backward case, the error signal is backward propagated through a filter to the asynchronous domain. Using such forward and backward propagation schemes reduces implementation complexity while providing optical device performance.

A method is presented for determining an offset frequency of a frequency comb. The method includes: generating a beam of light with a waveform that repeats regularly in the time domain and exhibits a frequency comb in the frequency domain; directing the beam of light towards a point of incidence on a material; and detecting oscillation of a photocurrent in the material that is caused by the beam of light. Of note, the beam of light has an optical bandwidth that includes light propagating at a first frequency and at a second frequency, where the first frequency is less than the second frequency and the ratio of the second frequency to the first frequency is n:m, where n=m+i, m is an integer greater than one, and n and i are positive integers. Additionally, the material has a band gap and the band gap is not more than n times the first frequency.

An optical receiver is provided with: an optical reception circuit which receives wavelength multiplexed light including signal light, converts the signal light into an electrical signal by coherent detection of the signal light using local oscillation light, and outputs the power of the local oscillation light, the bit error rate of the signal light and the electrical signal; and a controller which monitors the power of the local oscillation light and the bit error rate, calculates the signal-to-noise ratio of the signal light on the basis of the power of the local oscillation light and the bit error rate, and finds the number of wavelengths of the wavelength multiplexed light and the power per wavelength of the signal light on the basis of the signal-to-noise ratio and the power of the local oscillation light.

A communication network includes a coherent optics transmitter, a coherent optics receiver, an optical transport medium operably coupling the coherent optics transmitter to the coherent optics receiver, and a coherent optics interface. The coherent optics interface includes a lineside interface portion, a clientside interface portion, and a control interface portion.

A hyperspectral radiometer may comprise one or more antennas, a electro-optical modulator modulating the received RF signal onto an optical carrier to generate a modulated signal having at least one sideband; a filter filtering the modulated signal to pass the sideband to a photodetector; and a photodetector producing an electrical signal from which information of the RF signal can be extracted. In some examples, the optical sideband may be spatially dispersed to provide a plurality of spatially separate optical components to the photodetector, where the spatially separate optical components having different frequencies and correspond to different frequencies of the received RF signal. In some examples, the passed sideband may be mixed with an optical beam having a frequency offset from the optical carrier to form a combined beam having at least one optical signal component having a beat frequency from which information of the RF signal can be extracted.

An optical receiver is provided that includes a detector array of multiple detector elements, and processing circuits coupled to the multiple detector elements. The detector array is configured to receive light from an external source, mix the light with light from a local oscillator to generate a spatial fringe across the detector array. The multiple detector elements are configured to convert respective portions of the spatial fringe incident on the multiple detector elements to corresponding electrical signals. The processing circuits are configured to process the electrical signals. This includes the processing circuits configured to sum those of the corresponding electrical signals from one or more of the multiple detectors, and subtract the sum from a second sum of those of the corresponding electrical signals from one or more other of the multiple detectors.

Provided are a coherent optical receiver and a fabrication method thereof, the coherent optical receiver including a substrate, signal and local input waveguides extending in a first direction parallel to a top surface of the substrate and configured to receive an optical signal, a first optical circuit element including a first optical waveguide connected to the signal input waveguide and a trench provided in one side of the first optical waveguide in parallel to the first direction, a second optical circuit element including a second optical waveguide connected to the first optical waveguide, a slit crossing the second optical waveguide, and a wavelength plate inserted to the slit, and third optical circuit elements connected to the second optical circuit element, wherein the first to third optical circuit elements are monolithically integrated in the substrate.