An optical network communication system utilizes a coherent passive optical network (PON). The system includes an optical line terminal (OLT) having a downstream transmitter and an upstream receiver system configured for time-wavelength division coherent detection. The system further includes a splitter in operable communication with the OLT, and a plurality of optical network units (ONUs) in operable communication with the splitter. Each of the plurality of ONUs is configured to (i) receive downstream coherent burst signals from the OLT, and (ii) transmit at least one upstream burst signal to the OLT. The upstream receiver system further includes a power control module and a local oscillator (LO) configured to generate an optical LO signal The power control module is configured to adaptively control, in real-time, a power level of the optical LO signal.

An optical module includes: a casing; a printed circuit board (PCB) connected to a first side wall of the casing and configured to provide first electrical signals to an optical transmitter assembly; the optical transmitter assembly arranged in the casing and configured to convert the first electrical signals into first optical signals; an optical receiver adapter and an optical transmitter adapter arranged outside the casing and connected to a second side wall of the casing, wherein the optical transmitter adapter is configured to receive second optical signals; a first displacement prism arranged in the casing and configured to direct the second optical signals toward an optical receiver assembly; and the optical receiver assembly configured to convert the second optical signals into second electrical signals. At least one component of the optical receiver assembly is arranged in the casing.

Optical signal to noise ratios that more accurately characterize optical link noise are determined. As noise induced by an optical receiver does not generally vary with an input optical signal power, a power of an incoming optical signal is varied at the receiver. A resulting variation in noise measure represents a variation in link noise and does not include any variation caused by receiver noise, as receiver noise does not generally vary with optical signal power. Thus, the contribution of optical link noise can be discerned from other noise induced by the receiver itself. A more accurate characterization of optical link performance is thus provided.

First compensation circuitry includes a first digital filter compensating a phase difference between a phase of a symbol of a received signal and a sampling timing, and first filter coefficient calculation circuitry calculating a filter coefficient of the first digital filter as a first filter coefficient. Second filter coefficient calculation circuitry calculates, as a second filter coefficient, a filter coefficient for adaptive equalization that compensates distortion due to temporally changing polarization dispersion, based on an output of the first digital filter. Coefficient combination circuitry combines the first filter coefficient and the second filter coefficient. Second compensation circuitry includes a second digital filter which uses a filter coefficient combined by the coefficient combination circuitry and performs a compensation of the phase difference between the phase of the symbol of the received signal and the sampling timing, and a process of the adaptive equalization at the same time.

A signal processing device includes: a first conversion circuit that, among optical signals of channels included in wavelength division multiplexed optical signal, converts electric field signals that indicate electric field components of the optical signal of a predetermined channel, from time domain signals into frequency domain signals; a filter that passes the electric field signals converted into the frequency domain signals with a passband; a second conversion circuit that converts the electric field signals, from the frequency domain signals into the time domain signals; an amplitude measurement circuit that measures first amplitudes of the electric field signals and second amplitudes of the electric field signals; and a notification circuit that notifies a power measurement device that measures power of the optical signal of the predetermined channel, of the first amplitudes and the second amplitudes used in correction of a measurement error of the power of the optical signal.

Example polarization processing optical devices, methods, and systems are disclosed. A polarization processing optical device includes a polarization beam splitter (PBS), a polarization rotator (PR), a coupler, and a phase tuner (PT), where one port of the PBS is configured to input a continuous light source, and the other two ports of the PBS are respectively connected to the PR and one port of the coupler, the PR is connected to another port of the coupler, the PT is disposed on a connection between the PBS and the coupler or a connection between the PR and the coupler, at least one port of the coupler is configured to output single-polarization light, and the PT is configured to control output optical power of the coupler.

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

An integrated receiver chip comprising: a first end and a second end; at least one optical input port disposed at the first end; a polarization manipulation device optically connected to one of the at least one optical input port, the polarization manipulation device being adapted to split an optical signal into a first and a second optical signals; a first and a second dispersion compensators each optically connected to the polarization manipulation device, the first and the second dispersion compensators each being adapted to selectively induce a dispersion on an optical signal propagating through the dispersion compensator; and a first and a second photodetectors optically connected to the first and the second dispersion compensators, respectively.

An optical bench utilizing narrowband optical filters on precision rotary stages that can provide custom tuning of the operational frequencies of the optical bench while maintaining the ability to switch between narrowband and wideband operation thereof. The precision rotary filters may further provide dynamic reconfiguration of the optical bench to alternate frequencies for intersystem compatibility, the enablement of additional self-test capabilities, and easing the manufacturing tolerances thereof.

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.