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.

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.

In the examples provided herein, a system includes an input waveguide, where a first end of the input waveguide is coupled to a light-emitting optical transmitter to allow the emitted light to enter the input waveguide, and a first ring resonator tunable to be resonant at a first resonant wavelength, wherein the first ring resonator is positioned near the input waveguide to couple a light at the first resonant wavelength from the input waveguide to the first ring resonator. The system also has a bus waveguide positioned to couple the light at the first resonant wavelength in the first ring resonator to the bus waveguide, and a mechanism to wavelength-tune the first ring resonator to a particular wavelength.

Devices, computer-readable media and methods are disclosed for determining reachability for a wavelength connection in a telecommunication network. For example, a processor deployed in a telecommunication network may calculate a fiber loss on a link in the telecommunication network using optical power measurements and determine that a destination node of a wavelength connection is not reachable via a path that includes the link based upon the fiber loss of the link that is calculated. In one example, the determining is based upon a number of links in the path, an effective fiber loss for each link in the path, a penalty for nodes in the path, and an acceptable loss value. The processor may further perform a remedial action in response to determining that the destination node of the wavelength connection is not reachable via the path.

A test controller of a transmitting-side optical wavelength multiplexing transmission apparatus of the present invention includes a wavelength tunable filter controller configured to control a center wavelength and a wavelength band of an optical signal that a wavelength tunable filter transmits; and a test transponder controller configured to control a wavelength band of a test optical signal generated by a test transponder and a wavelength interval between the test optical signal and the optical signal that the wavelength tunable filter transmits. A test controller of a receiving-side optical wavelength multiplexing transmission apparatus of the present invention includes a wavelength tunable filter controller configured to control a center wavelength and a wavelength band of an optical signal that a wavelength tunable filter transmits; and a test transponder controller configured to control a center wavelength and a wavelength band of a test optical signal received by a test transponder.

A wavelength-tunable optical filter control apparatus in an optical access system that uses wavelength-multiplexed optical signal of a plurality of wavelength channels includes a wavelength-tunable optical filter configured to pass an optical signal of a specific wavelength channel among the plurality of wavelength channels; a light receiving element configured to convert the optical signal that has passed through the wavelength-tunable optical filter into an electrical signal; a signal quality determining unit configured to determine a quality of the electrical signal; and a wavelength-tunable optical filter control unit configured to acquire a light intensity of the electrical signal and control a wavelength of the wavelength-tunable optical filter based on the acquired light intensity and a determination result of the quality of the electrical signal.

A frequency offset processing method, apparatus, and a storage medium, where the method includes: determining a frequency offset of a preset channel in a wavelength selective switch (WSS); determining a correspondence between a frequency offset and a wavelength or a correspondence between a frequency offset and a pixel position based on the frequency offset of the preset channel; and determining a frequency offset of a traffic channel according to the determined correspondence.

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.

An OLT (2) includes one or more optical receivers (22) configured to receive optical signals of respective different wavelengths obtained by an AWG filter (4) demultiplexing a wavelength-multiplexed signal addressed to the terminal itself, and a supervisory controller (23) configured to transmit, to an ONU (3), a wavelength adjustment instruction to transit a wavelength to be used by an optical transmitter (32) for transmission of an optical signal, to set a difference between an optical received power of an optical signal received by any of the optical receivers (22) and a reference value of the optical received power within a threshold, the ONU (3) being a transmission source of the optical signal.

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.