Automatic optical link calibration systems and methods include an optical node with an Optical Add-Drop Multiplexer (OADM) multiplexer including a channel holder source; an optical amplifier connected to the OADM multiplexer and to a fiber span; an Optical Channel Monitor (OCM) configured to monitor optical spectrum before and after the optical amplifier; and a controller configured to obtain data associated with the fiber span including measurements from the OCM, determine settings of the channel holder source needed to meet a target launch power profile for the fiber span, and configure the channel holder source based on the determined settings.

Techniques are described for determining, with a first optical node, a correction factor indicative of an amount of optical power loss that a Raman amplifier in a second optical node causes in an optical signal having a first wavelength that is transmitted by the first optical node and received by the second optical node, transmitting, with the first optical node to the second optical node, information, based on the determined correction factor, that is to be used for determining a gain of the Raman amplifier, and transmitting, with the first optical node to the second optical node, an optical signal having a second wavelength that is to be amplified by the Raman amplifier.

A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the optical ports thereof. In an example embodiment, the supervisory optical circuit provides one or more pathways therethrough for supervisory optical signals, each of these pathways having located therein a respective narrow band-pass optical filter. The supervisory optical circuit further provides one or more pathways therethrough configured to bypass the corresponding narrow band-pass optical filters in a manner that enables backscattered light of any wavelength to cross into the optical path that has therein the unidirectional optical amplifier directionally aligned with the propagation direction of the backscattered light.

According to one example embodiment, a light-transmission-path-spectrum measurement device includes: a wavelength varying OTDR measurement unit that varies and generates a wavelength of measurement light to be transmitted to a first light transmission path, and also measures return light acquired from the measurement light being returned, by a repeater connected to the first light transmission path, via a second light transmission path connected to the repeater; an optical signal multiplexing unit that selects the wavelength of the measurement light being generated by the wavelength varying OTDR measurement unit, and outputs the selected wavelength to the first light transmission path; a control unit that controls the wavelength of the measurement light being generated by the wavelength varying OTDR measurement unit and the wavelength of the measurement light being selected by the optical signal multiplexing unit; and a measurement data processing unit.

Various example embodiments for supporting supervision in optical communication systems are presented. Various example embodiments for supporting supervision in optical communication systems may be configured to support supervision of an optical path including a remote optically pumped amplifier (ROPA) and, thus, supervision of the ROPA. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical supervisory paths configured to extract a pair of optical supervisory signals from an optical path in a first direction and to insert the pair of optical supervisory signals into an optical path in a second direction. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical time-domain reflectometer (OTDR) paths.

A method for determining timing information in an optical communication link includes transmitting a falling edge from a transceiver positioned at a near end of the optical communication link and simultaneously starting a first timer at the transceiver positioned at the near end of the link. The transmitted falling edge is received at a transceiver positioned at a far end of the link. A falling edge is transmitted from the transceiver positioned at the far end of the link after a response delay. The transmitted falling edge is received at the transceiver positioned at the near end of the link while the first timer is simultaneously terminated at the transceiver positioned at the near end of the link and the elapsed time is recorded. The total link delay is determined based on the elapsed time.

This application discloses an optical amplifier including a Raman fiber amplifier (RFA), a dynamic gain equalizer (DGE), a filter, an erbium-doped fiber amplifier (EDFA), an RFA gain controller, an EDFA gain controller, and an optical amplifier controller. The optical amplifier controller is configured to provide instructions to and receive feedback from the RFA and EDFA gain controllers. The RFA and the EDFA are configured to amplify an optical signal. The RFA gain controller is configured to control the RFA to adjust a gain. The EDFA gain controller is configured to control the EDFA to adjust a gain. The DGE adjusts insertion loss. The filter is configured to filter an amplified spontaneous emission signal produced in an optical amplification process of the RFA.

An optical transmission device includes a first detector, a generator, a second detector, and a controller. The first detector detects optical output power of an optical signal for each channel for input to a Mach-Zehnder unit that has asymmetric optical waveguides. The generator superimposes, based on the detected optical output power for each of the channels, a dither signal onto an optical signal in a specific channel from among the plurality of channels for input to the Mach-Zehnder unit. The second detector detects an amplitude value of the dither signal superimposed onto the optical signal in the specific channel output from the Mach-Zehnder unit. The controller adjusts a phase difference in the Mach-Zehnder unit such that the amplitude value of the dither signal superimposed onto the detected optical signal in the specific channel is less than a predetermined threshold.

Differentiating traffic signals from filler channels in optical networks includes obtaining power measurements of optical spectrum on an optical section in the optical network; analyzing the power measurements to differentiate signal type between traffic signals and Amplified Stimulated Emission (ASE) channel holders; and applying appropriate treatment to the optical spectrum based on the signal type. The analyzing is performed locally without any notification from upstream nodes of the optical spectrum.

Various example embodiments for supporting supervision in optical communication systems are presented. Various example embodiments for supporting supervision in optical communication systems may be configured to support supervision of an optical path including a remote optically pumped amplifier (ROPA) and, thus, supervision of the ROPA. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical supervisory paths configured to extract a pair of optical supervisory signals from an optical path in a first direction and to insert the pair of optical supervisory signals into an optical path in a second direction. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical time-domain reflectometer (OTDR) paths.