Embodiments of this application disclose an optical switch. The optical switch includes at least one first port, at least one second port, a first wavelength division multiplexing WDM apparatus, an optical splitter, an optical monitoring apparatus, and an optical switching apparatus. The first port is configured to transmit an input first optical signal to the first WDM apparatus, where the first optical signal is a multi-wavelength signal. The first WDM apparatus is configured to demultiplex the first optical signal. The optical splitter is configured to split a demultiplexed first optical signal to obtain a first sub-signal and a second sub-signal. The optical switching apparatus is configured to perform optical switching on the first sub-signal. The second port is configured to output a first sub-signal obtained after optical switching. The optical monitoring apparatus is configured to perform optical performance monitoring on the second sub-signal.

An optical transmitter includes: an optical modulator of a Mach-Zehnder type using an InP-based material; a bias controller configured to control a DC bias applied to the optical modulator; a monitor configured to monitor output light of the optical modulator to generate a monitor signal; and a corrector configured to correct a gain of the monitor signal in a direction in which wavelength dependency of insertion loss of the optical modulator is compensated according to a wavelength at a preceding stage of bias control by the bias controller.

An optical communication apparatus receives a signal in which optical signals each including multiplexed subcarriers are frequency multiplexed, and includes: transceivers to perform reception process on a processing target band in which any one of the optical signals is included and to calculate a frequency offset amount between local light and a reception target optical signal that is included in the processing target band and calculate a carrier frequency interval between the local light and an optical signal adjacent to the reception target optical signal; and a frequency control unit to calculate an adjustment amount when an optical communication apparatus that is a source of the optical signals adjusts the frequencies of the optical signals based on the frequency offset amount and the carrier frequency interval calculated by the transceivers and to transmit the calculated adjustment amount to the optical communication apparatus that is a source of the optical signals.

A transmission apparatus includes a demultiplexer configured to demultiplex a multiplexed signal including wavelength multiplexed signals having individual wavelength bands into a wavelength multiplexed signal for each of the wavelength bands, a detector configured to detect a power value of each of the wavelength multiplexed signals for each of the wavelength bands, first compensators configured to compensate for a tilt in the wavelength multiplexed signal based on the power value for each of the wavelength bands, second compensators configured to compensate for a power of the wavelength multiplexed signal for each of the wavelength bands so as to reduce a power difference among wavelength multiplexed signals after the tilt compensation based on the power value for each of the wavelength bands, and a multiplexer configured to multiplex each of the wavelength multiplexed signals after the power compensation and output a multiplexed signal.

In some embodiments, an apparatus includes a processor configured to receive a set of digital samples associated with a set of optical signals received at a coherent optical receiver. The set of digital samples is associated with a set of optical channels. Each optical channel from the set of optical channels is spaced from at least one adjacent optical channel from the plurality of optical channels. The processor is configured to calculate, for each optical channel from the set of optical channels, a spacing between that optical channel and at least one adjacent optical channel from the set of optical channels based on digital signal processing of the set of digital samples. The processor is configured to send a signal indicating, for each optical channel from the set of optical channels, the spacing between that optical channel and the at least one adjacent optical channel.

An optical channel monitor (OCM) may include a modulator to provide a modulation signal and a local oscillator (LO) to provide a modulated LO signal. The modulated LO signal may be created by modulating an LO signal based on the modulation signal. The OCM may include a mixer to generate a pair of mixed optical signals. The pair of mixed optical signals may be generated based on mixing the modulated LO signal and an input optical signal. The OCM may include an optical detector to provide, based on the pair of mixed optical signals, a first electrical signal corresponding to a coherent mixture of the input optical signal and the modulated LO signal. The OCM may include a synchronous demodulator to provide, based on the first electrical signal and the modulation signal, a second electrical signal representative of the optical power spectrum of the input optical signal.

According to examples, a wavelength identification and analysis sensor may include a wavelength transmitter, operably connectable to an input or output of a wavelength selective device of a wavelength division multiplex (WDM) network, to transmit test signals on a plurality of wavelengths into the input or output of the wavelength selective device of the WDM network. A wavelength analyzer is to detect returned signals from the input or output of the wavelength selective device of the WDM network, with each returned signal being associated with one of the transmitted test signals. Further, the wavelength analyzer is to analyze the returned signals and identify, based on the analysis of the returned signals, a wavelength associated with the input or output of the wavelength selective device of the WDM network.

A process for detecting a detuning which currently exists at a wavelength splitter within an optical fiber transmission network, comprises assessing expected values relating to at least two light sub-carriers, and determining actual values relating to said at least two light sub-carriers. A wavelength shift value which quantifies the existing detuning is obtained from a comparison between the expected and actual values. The process may be completed with updating a tuning of a light source from which the sub-carriers are derived, so as to reduce the wavelength shift.

There is provided an optical signal monitoring device and an optical signal monitoring system of a wavelength division multiplexing based network including: an input unit configured to receive each of downlink signals and uplink signals; a wavelength division multiplexing filter configured to separate the downlink signals and the uplink signals by wavelength; an optical power measurement module configured to measure optical power of each signal separated by wavelength; and a controller configured to determine whether an optical signal is abnormal based on optical power information measured by the optical power measurement module.

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.