Embodiments of this disclosure provide a method and apparatus for monitoring a modulation depth of a dither signal and an optical transmitter. The apparatus includes a detector to detect an optical signal output by a Mach-Zehnder modulator to obtain an electrical signal, a dither signal at a determined frequency is superimposed on a direct current bias voltage of the Mach-Zehnder modulator; a frequency-doubling dither signal synchronization detection module to perform synchronization detection on the electrical signal and a frequency-doubling dither signal at a frequency twice the determined frequency, to obtain an amplitude of a signal component contained in the electrical signal at a frequency identical to the frequency of the frequency-doubling dither signal A signal processor is to calculate a modulation depth of the dither signal superimposed on the direct current bias voltage according to the amplitude of the signal component at the frequency identical to the frequency of the frequency-doubling dither signal.

There is provided apparatuses to detect occurrence and location of damages on optical fiber links in advance by converting an optical span in optical network to an interferometry based sensing media. The interferometry based sensing media may enable detection of mechanical perturbation or mechanical vibration occurred on optical fiber links across optical network. The system employed with the interferometry based sensing media can detect occurrence of mechanical perturbation or mechanical vibration as well as discover the location of such event occurred using standard interferometry based sensing techniques.

There is provided an apparatus for fiber optic line continuity detection. The apparatus comprises an optical input connectable to a first optical fiber of a fiber optic line, an optical output connectable to a second optical fiber of the fiber optic line an optical interface unit configured to transmit and receive optical signals; and an optical switch having a first configuration and a second configuration. In the first configuration the optical switch is configured to pass optical signals received at the optical input to the optical interface unit and to pass optical signals received from the optical interface unit to the optical output. Whereas, in the second configuration the optical switch is configured to pass optical signals received at the optical input to the optical output.

Embodiments of this disclosure provide a method and apparatus for monitoring a modulation depth of a dither signal and an optical transmitter. The apparatus includes a detector to detect an optical signal output by a Mach-Zehnder modulator to obtain an electrical signal, a dither signal at a determined frequency is superimposed on a direct current bias voltage of the Mach-Zehnder modulator; a frequency-doubling dither signal synchronization detection module to perform synchronization detection on the electrical signal and a frequency-doubling dither signal at a frequency twice the determined frequency, to obtain an amplitude of a signal component contained in the electrical signal at a frequency identical to the frequency of the frequency-doubling dither signal A signal processor is to calculate a modulation depth of the dither signal superimposed on the direct current bias voltage according to the amplitude of the signal component at the frequency identical to the frequency of the frequency-doubling dither signal.

Techniques are provided for identifying and monitoring connections in an optical system. A plurality of optical ports is configured to receive a plurality of optical links that couple with one or more remote optical devices. At least one light source generates identification (ID) signals. At least one optical element configured to direct the ID signals into transmission paths from the source optical device to the remote optical device/s over the plurality of optical links. The remote optical device/s include one or more optical elements that direct the ID signals through a set of WDM filters and returns the ID signals. At least one optical element directs returned ID signals to an optical channel monitor. At least one microprocessor configured to execute control instructions to generate the ID signals and process one or more outputs of the optical channel monitor in response to the returned ID signals to identify the plurality of optical links.

An autonomous failure recovery method and a system for a fiber-optic communication system. The method comprises acquiring a real-time operation timing sequence of a digital high-speed serial transceiver of a fiber-optic communication system, and comparing the operation timing sequence against a pre-stored reference timing sequence of normal operation of the serial transceiver; when the operation timing sequence is inconsistent with the reference timing sequence, determining that failure of an optical path of the fiber-optic communication system has occurred; sending a pre-determined autonomous recovery timing sequence to the serial transceiver when the optical path is in a failure state, and performing an autonomous failure recovery operation of the fiber-optic communication system in response to the autonomous recovery timing sequence. The method and the system for a fiber-optic communication system achieve automatic troubleshooting and autonomous failure recovery for an optical path failure, thereby improving efficiency of troubleshooting and system recovery.

There is provided apparatuses to detect occurrence and location of damages on optical fiber links in advance by converting an optical span in optical network to an interferometry based sensing media. The interferometry based sensing media may enable detection of mechanical perturbation or mechanical vibration occurred on optical fiber links across optical network. The system employed with the interferometry based sensing media can detect occurrence of mechanical perturbation or mechanical vibration as well as discover the location of such event occurred using standard interferometry based sensing techniques.

A laser tuning system includes an optical transmitter having a tunable laser that transmits optical signals at various wavelengths to an optical fiber through an optical component, which attenuates a range of wavelengths of the optical signal. An optical detector detects optical returns that have been reflected from the fiber at points beyond the optical component. A tuning control module analyzes the optical returns in order to provide a tuning value for tuning the laser to a desired wavelength. As an example, the laser may be tuned in order to maximize or otherwise increase the amount of optical power passing through the optical component.

Methods and systems for an optical connection service interface may include, in an optical data link comprising an optical fiber coupling first and second transceivers, generating a signal for the transceivers at a low frequency, and communicating, utilizing the optical fiber, an optical data signal at a high frequency and an Optical Connection Service interface (OCSi) signal at an intermediate frequency. An optical signal may be modulated at the intermediate frequencies for the OCSi, and may be modulated and communicated to the second transceiver. The communicated modulated signal and the optical data signal may be detected utilizing a photodetector in the second transceiver. The detected optical signal may be demodulated, and an optical power of the optical data signal may be configured based on the demodulated signal.

A target constellation diagram determining method, a data sending method, and an apparatus are provided in accordance with the disclosure. The target constellation diagram determining method in accordance with the disclosure may include receiving, by a receiving device, training data that is generated and sent by a sending device based on each constellation point in an alternative constellation diagram. A detection region of each constellation point can then be determined based on a position of the training data in the alternative constellation diagram. A cumulative distance corresponding to the alternative constellation diagram can be obtained based on a distance between the detection regions of the constellation points. The method may include determining, based on cumulative distances corresponding to a plurality of alternative constellation diagrams, that an alternative constellation diagram with a largest cumulative distance is a target constellation diagram, and notifying the sending device of the target constellation diagram, so that the sending device modulates to-be-sent data based on the target constellation diagram.