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.

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).

One embodiment provides a system for measuring optical fiber channel loss in photonic communication. During operation, a first multiplexing device receives a first signal which is a photonic signal and a second signal which is a reference light signal transmitted by a first measuring device. In response, the first multiplexing device couples the first signal with the second signal, and transmits the coupled signal via an optical fiber channel to a second multiplexing device. The second multiplexing device separates the coupled signal into a separated first signal and a separated second signal, and transmits the separated second signal to a second measuring device. The system obtains indices related to a degree of loss of the optical fiber channel based on the separated second signal.

An optical transmission device includes an optical amplifier that optically amplifies a wavelength multiplexing signal which is input, a wavelength selective switch that splits, inserts, or transmits an optical signal of any wavelength of the wavelength multiplexing signal, an optical channel power monitor that detects power of each channel of the wavelength multiplexing signal which is input and the wavelength multiplexing signal which is output, and a controller that calculates an amount of change in the optical signal of each channel in which a gain of each channel between an input and an output to and from the device is steady, and adjusts an amount of attenuation of the wavelength selective switch, based on the power of each channel of the wavelength multiplexing signal that is detected by the optical channel power monitor.

A method comprises receiving streaming data in the form of peak readings developed from spectrum data produced by multiplexed optical sensors of one or more optical fibers. The streaming data comprises wavelength and intensity data associated with the sensors. The method comprises determining, for a particular fiber, whether a number of the peak readings is the same as, or differs from, an expected number, N, where N corresponds to a total number of sensors of the particular fiber. The method also comprises correcting anomalous streaming data in response to determining that the number of the peak readings differs from the expected number, N. The method further comprises storing nominal wavelength and intensity streaming data and the corrected wavelength and intensity streaming data in a structured data table indexed by fiber ID and sensor ID.

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.

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.

The performance of quantum key distribution by systems and methods that use wavelength division multiplexing and encode information using both wavelength and polarization of photons of two or more wavelengths. Multi-wavelength polarization state encoding schemes allow ternary-coded digits, quaternary-coded digits and higher-radix digits to be represented by single photons. Information expressed in a first radix can be encoded in a higher radix and combined with a string of key values to produce a datastream having all allowed digit values of that radix in a manner that allows eavesdropping to be detected without requiring the sender and receiver to exchange additional information after transmission of the information.

An optical device may include a dispersion element. The optical device may include a reflective optic to reflect an optical beam with a fixed offset perpendicular to a dispersion direction of the dispersion element and with a negative offset in the dispersion direction of the dispersion element. The reflective optic may be aligned to the dispersion element to offset an optical beam with respect to the dispersion element and to cause the optical beam to pass through the dispersion element on a plurality of passes, offsetting the optical beam on each of the plurality of passes.

The performance of quantum key distribution by systems and methods that use wavelength division multiplexing and encode information using both wavelength and polarization of photons of two or more wavelengths. Multi-wavelength polarization state encoding schemes allow ternary-coded digits, quaternary-coded digits and higher-radix digits to be represented by single photons. Information expressed in a first radix can be encoded in a higher radix and combined with a string of key values to produce a datastream having all allowed digit values of that radix in a manner that allows eavesdropping to be detected without requiring the sender and receiver to exchange additional information after transmission of the information.