An optical reception apparatus (1) of the present invention includes: a local oscillator (11) outputting local oscillation light (22); an optical mixer (12) receiving a multiplexed optical signal (21) and the local oscillation light, and selectively outputting an optical signal (23) corresponding to the wavelength of the local oscillation light from the multiplexed optical signal; a photoelectric converter (13) converting the optical signal (23) output from the optical mixer into an electric signal (24); a variable gain amplifier (15) amplifying the electric signal (24) to generate an output signal (25) whose output amplitude is amplified to a certain level; a gain control signal generating circuit (16) generating a gain control signal (26) for controlling the gain of the variable gain amplifier (15); and a monitor signal generating unit (17) generating a monitor signal (27) corresponding to the power of the optical signal (23) using the gain control signal (26).

Automatic optical link calibration systems and methods include an optical node with an Optical Add-Drop Multiplexer (OADM) multiplexer including a channel holder source; an optical amplifier connected to the OADM multiplexer and to a fiber span; an Optical Channel Monitor (OCM) configured to monitor optical spectrum before and after the optical amplifier; and a controller configured to obtain data associated with the fiber span including measurements from the OCM, determine settings of the channel holder source needed to meet a target launch power profile for the fiber span, and configure the channel holder source based on the determined settings.

An optical receiver module which receives a first optical signal including a continuous signal or a burst signal includes: a variable optical attenuator which adjusts the first optical signal to output a second optical signal; a semiconductor optical amplifier which amplifies the second optical signal to output a third optical signal; and a controller which controls an output of at least one of the variable optical attenuator and the semiconductor optical amplifier so as to cause the semiconductor optical amplifier to operate in a region in which gain saturation of the semiconductor optical amplifier does not occur, on the basis of at least one of: a power obtained by suppressing an outside portion of the wavelength band of the first optical signal in the third optical signal; and a power obtained by extracting the outside portion of the wavelength band of the first optical signal in the third optical signal.

Systems and methods for a system-level Erbium-Doped Fiber Amplifier (EDFA) optical amplifier efficiency metric. The efficiency metric is a single metric that summarizes optical amplifier behavior and has a predictable behavior over various different optical amplifier settings. Specifically, the efficiency metric is simple and elegant. The simplicity is based on the fact the efficiency metric is determined from available data in an optical amplifier, not requiring external monitoring equipment, dithering, etc. The elegance is based on the fact the efficiency metric covers different optical amplifier settings, multiple pumps, etc. and is shown to reflect degradation with these differences in real-world systems accurately. Specifically, the efficiency metric is designed to reflect health in a multiple pump optical amplifier, providing a single value that represents the total pump currents across all of the multiple pumps.

Example fiber amplifiers and gain adjustment methods for the fiber amplifiers are described. One example fiber amplifier includes a first power amplifier, a wavelength level adjuster, and a controller, where the first power amplifier and the wavelength level adjuster are sequentially connected. The controller includes a first input end and a control output end. The first input end is configured to receive an input optical signal of the fiber amplifier, and the control output end is configured to output a first amplification control signal to the first power amplifier, and output an adjustment control signal to the wavelength level adjuster. The wavelength level adjuster is configured to perform power adjustment on each wavelength based on the adjustment control signal.

An optical system including a forward and a backward Raman pump module positioned along a transmission fiber; a noise matrix computing module configured to: determine, for first gains of the optical signal, a first noise associated with the first gain of the forward Raman pump; determine, for second gains of the optical signal, a second noise associated with the second gain of the backward Raman pump module; generate a noise matrix based on i) the first noise for each first gain of the forward Raman pump module and ii) the second noise for each second gain of the backward Raman pump module; identify a span loss of the optical signal as the optical signal is transmitted along the transmission fiber; identify a combination of a particular first gain of the forward Raman pump module and a particular second gain of the backward Raman pump module.

Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.

Systems and methods for measuring accumulated power losses over a fiber link are described in the present disclosure. According to one embodiment, a method includes the step of measuring accumulated losses over a fiber link. The method also includes the step of at least partially compensating for the measured accumulated losses. In response to determining that there is a compensation shortfall with respect to the accumulated losses, the method includes the step of transmitting the compensation shortfall to one or more downstream controllers.

Systems and methods for automatic link calibration include subsequent to installation of equipment for the amplified optical section, obtaining power measurements of optical spectrum in the optical section; obtaining properties of fiber in the amplified optical link; analyzing the power measurements and the properties of the fiber to determine settings for the equipment for calibration thereof; and automatically configuring the settings for the equipment. The settings are based on the power measurements and the properties of the fiber to achieve a target launch power per span in the amplified optical section, and wherein the target launch power is based on Optical Signal-to-Noise Ratio (OSNR) and non-linearity in the amplified optical section.

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.