Communication of light signals and optical cables can be managed to mitigate error associated with using optical cables to communicate light signals. A communication management component (CMC) can embed respective timing synchronization pulses in respective lights signals having respective wavelengths. The light signals can be typical light signals or can be squeezed and twisted to generate a desired twisted light signal. The light signals can be transmitted via the optical cable to a receiver. A CMC, at the receiver end, can determine error associated with the transmission of the light signals via the optical cable and respective characteristics of the respective light signals, including respective arrival times of the respective timing synchronization pulses and respective light intensity or power levels of the respective light signals. From the respective characteristics, CMC can determine a compensation action to perform mitigate the error with regard to subsequent transmissions of light signals.

Methods and systems for automated health assessment of fiber optic links of a fiber optic communication system are described. Tables are used to describe the fiber optic links, including access addresses to communication modules used in the links. Telemetry data representative of operation of the communication modules can be read via the access addresses into a central station. OTDR/OFDR measurement data of fiber optic segments used in the links can be read via the access addresses into the central station. The telemetry and/or OTDR/OFDR measurement data can be used by the central station for comparison against reference data to assess health of the links. The communication modules locally and continuously capture the telemetry data to detect transient events that may be the result of tampering of the links.

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).

The receiving-side system (10) includes a smaller number of optical reception front ends (12) than the number of a plurality of wavelength-multiplexed subcarrier signals. Each of the optical reception front ends (12) is configured to receive two or a plurality subcarrier signals of the plurality of subcarrier signals. A frequency offset monitoring unit (22) monitors frequency offsets of the respective subcarrier signals received by the optical reception front end (12). A light source frequency control unit (24) controls at least one of a light source frequency of the transmitting-side system (2) and a light source frequency of the receiving-side system (10) based on a result of the monitoring performed by the frequency offset monitoring unit (22).

A system may include a receiver configured to receive a communications signal from a transmitter and processing circuitry configured to: determine at least one frequency characteristic of the communications signal and compare the at least one frequency characteristic to at least one verified frequency characteristic stored by a memory associated with the processing circuitry to determine whether the transmitter is a verified transmitter. In some examples, the transmitter, receiver and communications signal are an optical transmitter, and optical receiver, and an optical signal, respectively.

A method and system is described. A signal indicative of a failure of a first channel within a plurality of channels of a transmission signal traversing a signal working path in a network is received. The signal working path has a headend node, a tail-end node and an intermediate node. The first channel has a frequency band and a power level prior to failing. The signal working path is associated with a protection path. The protection path includes the intermediate node, optical cross-connects, and a transmitter supplying (ASE) light. The transmitter is activated to supply the ASE light within a frequency band and having a power level corresponding to the frequency band and power level associated with the first channel. The ASE light is supplied to a cross-connect, such that the cross-connect provides a transmission signal including the ASE light.

A method and device for controlling a wavelength of a light emitting assembly. The device comprises a microcontroller, a light emitting assembly temperature control unit, an analog-to-digital converter, a digital-to-analog converter, a storage unit, a thermistor of a negative temperature coefficient in a TOSA component, and a TEC assembly. The microcontroller comprises an ADC input interface, a DAC output interface, a GPIO output interface, an external communication interface, and a memory interface. The light emitting assembly temperature control unit comprises a turn-off enable control circuit, a temperature detecting circuit, an error amplification-comparison-compensation unit, a TEC voltage/current limitation circuit, a TEC voltage/current detecting circuit, and a TEC differential voltage driver. The method and device are simple and flexible, implements a precise control of the wavelength, and also considers an adjustment function of the wavelength.

A wavelength detection system may include one or more wavelength detection stages configured to receive at least a portion of an input light signal, where each stage may include a splitter to split a portion of the input light signal into two arms, a 90-degree optical hybrid, and two differential detectors configured to generate I-channel and Q-channel differential signals based on the outputs from the 90-degree optical hybrid. Further, a free spectral range is associated with an optical path length difference between the two arms of each stage. The system may further include a logic device to receive at least one set of detection signals including I and Q channel differential signals associated with different free spectral ranges and determine the wavelength of the input light signal based on an arctangent of a ratio of the Q-channel and I-channel differential signals for at least one set of detection signals.

A wavelength-setting auxiliary device according to an embodiment of the inventive concept includes an optical wavelength analyzer configured to transmit a test signal having a first wavelength to an optical line terminal, and to execute a central wavelength detection algorithm based on a result of detecting power of a return signal for the test signal to set optical wavelength information of a tunable optical module, and a connector connected to the tunable optical module for interfacing data transmitted between the optical wavelength analyzer and the tunable optical module.

An optical transmission apparatus, includes, a light source configured to output a plurality of light beams having different wavelengths to an optical fiber, a receiver configured to receive, from the optical fiber, a reflected light beam corresponding to each of the wavelengths of the plurality of light beams, and a signal processing circuit configured to estimate a polarization fluctuation portion based on a polarization state of the received reflected light beam corresponding to each of the plurality of wavelengths.