Systems and method include a detector communicatively coupled to a fiber span; and processing circuitry connected to the detector and configured to digitally sample and process an output of the detector, detect phase changes in the output, and identify an electrostrictive response of the fiber span based on the detected phase changes and based on a dependence of the detected phase changes with frequency. A property of the fiber span can be determined on the electrostrictive response. The property of the optical fiber can include one or more of optical fiber material type, optical fiber material property, optical fiber area, optical fiber geometry, optical fiber condition, optical fiber stress and strain, optical fiber temperature. and optical fiber radiation exposure.

A system includes an optical transmitter including a transmitter Phase Lock Loop (PLL) circuit; an optical receiver connected to the optical transmitter and including a receiver PLL circuit; and circuitry configured to inject a test stimulus to a clock causing jitter in one of the transmitter PLL circuitry and the receiver PLL circuit, wherein the test stimulus is set for characterizing the jitter tolerance of optical receiver. As well, a circuit that injects SOP transient at the transmitter is included. It is configured to test the tolerance of optical receiver to handle fast change in the SOP state. The optical receiver is configured to determine if the system is operational at a jitter value due to the test stimulus based on compliance to one or more thresholds including any of a target Bit Error Rate, a Forward-Error-Correction (FEC) hit, and a jitter Root Mean Square (RMS).

A system includes a processor communicatively coupled to an Amplifier Stimulated Emission (ASE) source and an optical receiver, wherein the processor is configured to cause transmission of one or more shaped ASE signals, from the ASE source, on an optical fiber, obtain received spectrum of the one or more shaped ASE signals from the optical receiver connected to the optical fiber, and characterize the optical fiber based in part on a nonlinear skirt and/or center dip depth in the received spectrum of the one or more shaped ASE signals. The one or more shaped ASE signals can be formed by the ASE source communicatively coupled to a Wavelength Selective Switch (WSS) that is configured to shape ASE from the ASE source to form the one or more shaped ASE signals with one or two or multiple peaks and with associated frequency.

An optical device has an optical transmitter circuit formed in a substrate, a first port configured to output an optical signal generated by the optical transmitter circuit from an edge of the substrate during services and to input a test light from the edge of the substrate during a test, and a photodetector configured to detect the test light input from the first port.

Photonically integrated normal incidence photodetectors (NIPDs) and associated in-plane waveguide structures optically coupled to the NIPDs can be configured to allow for both in-plane and normal-incidence detection. In photonic circuits with light-generation capabilities, such as integrated optical transceivers, the ability of the NIPDs to detect in-plane light is used, in accordance with some embodiments, to provide self-test functionality.

A photonics system includes a transmit photonics module and a receive photonics module. The photonics system also includes a transmit waveguide coupled to the transmit photonics module, a first optical switch integrated with the transmit waveguide, and a diagnostics waveguide optically coupled to the first optical switch. The photonics system further includes a receive waveguide coupled to the receive photonics module and a second optical switch integrated with the receive waveguide and optically coupled to the diagnostics waveguide.

An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at a test modulation frequency F. COR performance parameters are determined by comparing two frequency components of the COR output. CMRR is determined based on a strength of a direct detection spectral line at the modulation frequency relative to that of spectrally-shifted lines at (Ff). GDV information is obtained by modulating one of the lights at two phase-locked frequencies, such as F and 2F, and comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two frequencies.

An active optical cable includes: a first connector; a second connector; an optical fiber cord that connects the first connector to the second connector; and a power supply line that connects the first connector to the second connector power. The first connector includes a control circuit that carries out a fault test for the optical fiber cord when the first connector or the second connector is in an unconnected state at a time point of commencement of supply of power to the first connector and the second connector.

There is provided a transmission apparatus including a transmitter configured to modulate a signal to a first signal having a first wavelength and a signal to a second signal having a second wavelength, and transmit the first signal and the second signal to a transmission line so that the second signal is varied in accordance with variation in an amount of cross phase modulation of the first signal passing through each position on the transmission line, and a signal processor configured to include at least one of a logic device and a processor, and configured to add an amount of chromatic dispersion at which a remaining amount of chromatic dispersion of the first wavelength at a certain position on the transmission line is equal to zero to the first wavelength in the transmission of the first signal and the second signal.

An example system includes non-transitory machine-readable storage storing calibration data sets. A calibration data set includes parameter values that vary non-linearly. Each of the calibration data sets is temperature-specific. The example system also includes channels over which signals pass to and from units under test (UUTs). A channel includes input circuitry to receive a signal of the signals and to obtain a first parameter based on the signal; and correction circuitry to obtain a second parameter based on the first parameter and based on the calibration data set. The second parameter includes a calibrated version of the first parameter. The calibration data set is selectable based on temperature.