A monitoring and calibration apparatus for an optical networking device such as ROADM is provided. Reflectors are integrated into the device, for example at the ends of optical interconnect cables. The reflectors reflect light in specific monitoring wavelengths and pass other wavelengths such as those used for communication. A light source emits monitoring light which is reflected by the reflector and measured by a detector to measure the integrity of optical paths. The optical paths can include optical cables and cable connectors. Path integrity between different modules of the device can therefore be monitored. Multiple reflectors, reflecting light in different wavelengths, can be placed in series along the same optical path and used to monitor multiple segments of the path. A wavelength selective switch (WSS) of the device can be used to route monitoring light to different optical paths. The WSS also operates to route communication signals in the device.

An optical module has an optical amplifier that amplifies an optical signal in which multiple wavelengths are multiplexed, an optical demultiplexer that separates the multiple wavelengths from the optical signal having been amplified by the optical amplifier, a first photodetector that monitors the optical signal at an input side of the optical amplifier, a second photodetector that monitors each of the multiple wavelengths at an output side of the optical demultiplexer, and a control circuit that controls a center wavelength of a filter of the optical demultiplexer based upon a first output from the first photodetector and a second output from the second photodetector.

Example embodiments of the present invention relate to programmable ROADMs used to construct optical nodes. Example embodiments include wavelength switches and waveguide switches, wherein the waveguide switches may be programmed to direct wavelength division multiplexed optical signals to and from the wavelength switches.

A measurement system is a measurement system inspecting an optical transmission line configured by connecting a plurality of optical cables, each of which includes a plurality of optical fibers, wherein the optical transmission line includes a plurality of optical fiber lines configured by connecting the plurality of optical fibers in the plurality of optical cables, the measurement system including: a first measurement device configured to be disposed at a first end of the optical transmission line; and a second measurement device configured to be disposed at a second end of the optical transmission line, wherein the first measurement device and the second measurement device perform a first measurement to inspect whether the optical cable is misconnected, and a second measurement to inspect the plurality of optical fiber lines in a case where it is determined that there is no misconnection in the first measurement.

A method including determining how many optical channel (OCh) paths are available for border node pair connections; determining which of the OCh paths satisfy a preselected latency threshold; and reporting the OCh paths that satisfy the preselected latency threshold to a service coordinator.

An acoustic emission wave detection system and an acoustic emission wave detector are provided. The acoustic emission wave detection system includes an acoustic emission wave detector, a photoelectric converter, and a determination processor. The acoustic emission wave detector includes a housing, an optical fiber that guides light from a wideband light source into the housing, and an FBG housed in the housing and having a diffractive grating that reflects light guided into the housing. The FBG is fixed on a side of the other end in the housing such that the light guided into the housing is received by one end thereof. An acoustic emission wave from a high-voltage apparatus is received by the other end thereof. Due to the insulation resistance of the FBG, the acoustic wave detector can be installed close to or in contact with the high-voltage apparatus without introducing discharges or noise from the high-voltage apparatus.

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 monitoring circuit obtains a light output proportional to only an input optical signal, independent of wavelength, by adding a light split circuit to the configuration in the related art, or changing the light split circuit to a light trifurcation circuit. In addition, wavelength monitoring with high accuracy is possible while improving the resistance to noise. The extraction of the light output proportional to only the input optical signal is performed by a light split circuit for input light at the top stage of the wavelength monitoring circuit or a light split circuit for interference in a stage in the middle of the circuit. The changed light split circuit causes the MZI included in the wavelength monitoring circuit to operate in a state of losing the balance of the configuration or the optical signal level, and increases the signal level near the bottom portion of the transmission characteristics.

A device may provide a signal with a first wavelength and a second wavelength to a fiber cable, and may receive an intensity change measurement of backscattered light based on the first wavelength of the signal. The device may receive a differential phase change measurement of the backscattered light based on the second wavelength of the signal, and may determine whether there is a fiber loss change, a fiber length change, and/or a fiber cut associated with the fiber cable based on the intensity change measurement. The device may determine whether there is an abnormal event associated with the fiber cable based on the differential phase change measurement, and may report one or more of the fiber loss change, the fiber length change, the fiber cut, or the abnormal event.

An optical network unit is configured to send a plurality of optical signals with different wavelengths to an optical line terminal. The optical signals in the plurality of optical signals carry indicating information. The indicating information is used to indicate the wavelength serial number of the optical signal and the temperature information of the laser chip when the optical signal is generated. The optical unit is further configured to receive temperature adjustment information from the optical line terminal; and adjust, based on the temperature adjustment information, the emission wavelength of the laser by adjusting the temperature of the laser chip.