Optical transmission apparatus, method for setting wavelength, and optical transceiver

1. An optical transmission apparatus comprising:

a plurality of optical transceivers including an optical transceiver; and

a wavelength multiplexer and demultiplexer configured to multiplex lights output from the respective plurality of optical transceivers, output a multiplexed light to an optical transmission line, receive a wavelength multiplex light from the optical transmission line, demultiplex the received wavelength multiplex light, and output the demultiplexed lights to the respective plurality of optical transceivers, wherein

the optical transceiver is configured to

generate a test light for each wavelength assignable to the wavelength multiplex light to transmit the test light to the optical transmission line via the wavelength multiplexer and demultiplexer,

detect a reflected light for the test light from the optical transmission line,

calculate a distance from the reflected light that is associated with each of the test light for the each wavelength that has transmitted,

select a wavelength having a longest distance among the distances for the respective wavelengths according to the calculated distances, and

set the wavelength having the longest distance, as a wavelength to be assigned to the signal light in the optical transceiver.

2. The optical transmission apparatus according to claim 1 , wherein

the optical transceiver is configured to

in a state in which the plurality of optical transceivers are coupled to connectors having different transmission wavelengths in the wavelength multiplexer and demultiplexer, set a wavelength having a longest distance among the distances for the respective wavelengths, as a wavelength to be assigned to the signal light in the optical transceiver coupled to a connector included in the connectors.

3. The optical transmission apparatus according to claim 1 , wherein

the optical transceiver is configured to

generate the test light having a wavelength other than wavelengths currently being used in the wavelength multiplex light among wavelengths assignable to the wavelength multiplex light.

4. The optical transmission apparatus according to claim 1 , wherein

the optical transceiver is configured to

in a state in which an optical amplifier for amplifying the wavelength multiplex light is not disposed over the optical transmission line, refer to a list of pulse widths measurable up to maximum distances for each power of the test light,

select a first pulse width with which the power of the test light is less than power of a signal light in the optical transceiver,

generate a first test light based on the selected first pulse width and a first pulse interval of the maximum distance,

transmit the first test light to the optical transmission line,

detect a first reflected light for the first test light from the optical transmission line,

calculate a distance that the first test light for the each wavelength from the first reflected light for the each wavelength being transmitted,

when wavelength assignment to the optical transceiver for the wavelength with which a distance of the first test light is the longest fails,

calculate a second pulse interval and a second pulse width of a second test light based on the distance of the first test light,

generate the second test light based on the second pulse interval and the second pulse width of the second test light,

transmit the second test light to the optical transmission line,

detect a second reflected light for the second test light from the optical transmission line,

calculate a distance that the second test light for each of the wavelengths from the second reflected light for each of the wavelengths being transmitted, and

set a wavelength with which the distance is the longest among the distances of the second test lights, as a wavelength to be assigned to the signal light in the optical transceiver.

5. A method for setting a wavelength to be executed by an optical transmission apparatus, the method comprising:

generating a test light for each wavelength;

transmitting the generated test light to an optical transmission line;

detecting a reflected light for the test light from the optical transmission line;

calculating a distance from the detected reflected light that is associated with each of the test light for each of the wavelength that has transmitted;

selecting a wavelength having a longest distance among distances, each of the distances correspond to the each wavelength according to the calculated distances, and

setting the wavelength having the longest distance, as a wavelength to be assigned to a signal light to be generated by an optical transceiver included in the optical transmission apparatus.

6. The method according to the claim 5 , wherein

processing for setting the wavelength includes,

in a state in which a plurality of optical transceivers including the optical transceiver are coupled to connectors having different transmission wavelengths in a wavelength multiplexer and demultiplexer, setting a wavelength with which the distance is the longest among the distances for the respective wavelengths as a wavelength to be assigned to the signal light in the optical transceiver coupled to a connector included in the connectors.

7. The method according to the claim 5 , wherein the generating includes

generating the test light having a wavelength other than wavelengths currently being used in a wavelength multiplex light among wavelengths assignable to the wavelength multiplex light.

8. The method according to the claim 5 , wherein

the generating includes,

in a state in which an optical amplifier for amplifying a wavelength multiplex light is not disposed over the optical transmission line,

referring to a list of pulse widths measurable up to maximum distances for each power of the test light,

selecting a first pulse width with which the power of the test light is less than power of a signal light in the optical transceiver, and

generating a first test light based on the selected first pulse width and a first pulse interval of the maximum distance of the optical transceiver,

the processing for transmitting the generated test light to the optical transmission line includes

transmitting the first test light to the optical transmission line,

the processing for detecting the reflected light includes

detecting a first reflected light for the first test light from the optical transmission line, and

the processing for calculating the distance includes

calculating a distance that the first test light for the each wavelength from the first reflected light for each of the wavelengths being transmitted,

further comprising:

when wavelength assignment to the optical transceiver for the wavelength with which a distance of the first test light is the longest fails,

calculating a second pulse interval and a second pulse width of a second test light based on the arrival distance of the first test light,

generating the second test light based on the second pulse interval and the second pulse width of the second test light,

transmitting the second test light to the optical transmission line,

detecting a second reflected light for the second test light from the optical transmission line,

calculating a distance that the second test light for the each wavelength from the second reflected light for the each wavelength being transmitted, and

setting a wavelength with which the distance is the longest among the distances of the second test lights, as a wavelength to be assigned to the signal light in the optical transceiver.

9. An optical transceiver comprising:

an optical modulator configured to generate a test light for each wavelength assignable to a wavelength multiplex light obtained by multiplexing signal lights having different wavelengths from respective optical transceivers by a wavelength multiplexer and demultiplexer and output the wavelength multiplex light to an optical fiber;

a detector configured to detect a reflected light for the test light from the optical fiber; and

a processor configured to:

calculate a distance based on the reflected light that is associated with the test light for each of the respective wavelengths, and

a wavelength having a longest distance among the distances for the respective wavelengths according to the calculated distances, and set the wavelength having the longest distance, as a wavelength to be assigned to the signal light in the optical transceiver.