A wavelength control system, method, and apparatus are described in the present disclosure. An example method include: adjusting powers of subcarriers on a super channel to a same power, where the subcarriers of the super channel includes consecutive subcarriers, a subcarrier i1, a subcarrier i, and a subcarrier i+1; obtaining Q values of the subcarrier i1 and the subcarrier i+1, where the Q values indicate performance of the subcarriers; calculating a Q value difference between the Q value of the subcarrier i+1 and the Q value of the subcarrier i1, and calculating a difference between the Q value difference and a pre-obtained reference value of the subcarrier i; determining whether the absolute value of the difference is not less than the pre-obtained allowable frequency offset value, and adjusting a center wavelength of the subcarrier i according to the difference.

A communication device of the disclosure includes: a first terminal that outputs a power supply voltage; a second terminal coupled directly or indirectly to the first terminal; a communication section that operates on a basis of the power supply voltage to communicate with a communication peer; and a communication controller that sets the communication section to be in an ON state or in an OFF state on a basis of a voltage on the second terminal.

Optical fiber data communications are described. A comb laser can provide light at a first wavelength and a second wavelength. Using that light, polarization multiplexing circuitry can generate an optical signal having different polarization components and transceivers can transmit the optical signal having the first wavelength and a probe having the second wavelength via an optical fiber. A polarimeter can determine characteristics of the polarization of the probe. Based on the characteristics, a polarization controller can adjust a polarization of the optical signal. The optical signal can then be split into different polarization components.

Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.

Optical fiber data communications are described. A comb laser can provide light at a first wavelength and a second wavelength. Using that light, polarization multiplexing circuitry can generate an optical signal having different polarization components and transceivers can transmit the optical signal having the first wavelength and a probe having the second wavelength via an optical fiber. A polarimeter can determine characteristics of the polarization of the probe. Based on the characteristics, a polarization controller can adjust a polarization of the optical signal. The optical signal can then be split into different polarization components.

Using pump-probe measurements on multi-span optical links may result in the determination of one or more of the following: 1) wavelength-dependent power profile and gain evolution along the optical link; 2) wavelength-dependent dispersion map; and 3) location of regions of high polarization-dependent loss (PDL) and polarization-mode dispersion (PMD). Such measurements may be a useful diagnostic for maintenance and upgrade activities on deployed cables as well as for commissioning new cables.

OADM processes input light containing reference light and multiplexed optical signals. A splitter splits the input light to generate first and second input light. A receiver generates an electric signal representing the second input light. An estimator estimates a difference in optical frequency between the reference light and a specified optical signal based on the electric signal. Alight source generates first and second light. An optical frequency of the second light is shifted by the estimated difference with respect to that of the first light. A demodulator generates a dropped signal representing the specified optical signal. A drive signal generator generates a drive signal in accordance with an inverted signal of the dropped signal. A modulator modulates the second light with the drive signal to generate a modulated optical signal. The first input light, the first light and the modulated optical signal are input to non-linear optical medium.

A communication device of the disclosure includes: a first terminal that outputs a power supply voltage; a second terminal coupled directly or indirectly to the first terminal; a communication section that operates on a basis of the power supply voltage to communicate with a communication peer; and a communication controller that sets the communication section to be in an ON state or in an OFF state on a basis of a voltage on the second terminal.

A method for measuring asymmetry in propagation delay of first and second links which connect a first node to a second node of a communication network. The method comprises measuring (101) a round trip delay of the first link. The round trip delay can be measured by transmitting (102) a test signal from the first node to the second node over the first link and receiving a reply to the test signal from the second node over the first link. The method further comprises measuring (105) a round trip delay of the second link. The round trip delay can be measured by transmitting (106) a test signal to the second node over the second link and receiving a reply to the test signal from the second node over the second link. A difference in the propagation delay of the first link with respect to the second link is determined (109) using the measured round trip delays of the first link and the second link.

A communications device is disclosed and includes: a first acquiring unit for acquiring first specific wavelength light and second specific wavelength light from a first optical path; a first receiving unit for converting the first specific wavelength light coming from the first acquiring unit into a first electrical signal; a first control unit for sending a first modulating signal to a first loopback unit according to the first electrical signal coming from the first receiving unit; and the first loopback unit for modulating the second specific wavelength light coming from the first acquiring unit according to the first modulating signal, and looping the modulated second specific wavelength light back to a second optical path, where a transmission direction of an optical signal in the second optical path is opposite to a transmission direction of an optical signal in the first optical path. The present invention further discloses a communications method.