Device, system and method for transmitting wavelength division multiplexed optical signal

A transmission device for which a first work path and a second work path are established in a first degree and a first protection path and a second protection path respectively corresponding to the first work path and the second work path are established in a second degree, the transmission device comprising:

• a switch equipped with a plurality of optical ports;
• a first optical signal generator, optically connected to a first optical port among the plurality of optical ports, and configured to generate a first optical signal with a first wavelength that is transmitted through the first work path;
• a second optical signal generator, optically connected to a second optical port among the plurality of optical ports, and configured to generate a second optical signal with a second wavelength that is transmitted through the second work path;
• a monitor light generator, optically connected to a third optical port among the plurality of optical ports, and configured to generate monitor light by using a wavelength tunable light source;
• a wavelength selective switch configured to select light with a designated wavelength from light guided toward the second degree;
• and
• a controller configured to control the wavelength selective switch, wherein
• the switch guides the first optical signal that arrives at the first optical port and the second optical signal that arrives at the second optical port toward the first degree, and guides the monitor light that arrives at the third optical port toward the second degree,
• when the monitor light generator generates monitor light with the first wavelength,
• the wavelength selective switch selects the monitor light with the first wavelength guided from the switch and outputs the selected monitor light to the second degree,
• the controller determines a state of the wavelength selective switch with respect to the first wavelength in a manner such that a power of the monitor light with the first wavelength output from the wavelength selective switch approaches a target level, and
• the controller stores first state data that represents the state of the wavelength selective switch determined with respect to the first wavelength in a memory, and
• when the monitor light generator generates monitor light with the second wavelength,
• the wavelength selective switch selects the monitor light with the second wavelength guided from the switch and outputs the selected monitor light to the second degree,
• the controller determines a state of the wavelength selective switch with respect to the second wavelength in a manner such that a power of the monitor light with the second wavelength output from the wavelength selective switch approaches the target level, and
• the controller stores second state data that represents the state of the wavelength selective switch determined with respect to the second wavelength in the memory.

A transmission device that is connected to a first degree and a second degree, the transmission device comprising:

• a switch equipped with a plurality of optical ports;
• a first optical signal generator, optically connected to a first optical port among the plurality of optical ports, and configured to generate a first optical signal with a first wavelength that is transmitted through the first degree;
• a second optical signal generator, optically connected to a second optical port among the plurality of optical ports, and configured to generate a second optical signal with a second wavelength that is transmitted through the second degree;
• and
• a monitor light generator, optically connected to a third optical port among the plurality of optical ports, and configured to generate monitor light by using a wavelength tunable light source;
• when the monitor light generator generates monitor light with the first wavelength, the switch guides the first optical signal that arrives at the first optical port toward the first degree and guides the second optical signal that arrives at the second optical port and the monitor light that arrives at the third optical port toward the second degree, and
• when the monitor light generator generates monitor light with the second wavelength, the switch guides the first optical signal that arrives at the first optical port and the monitor light that arrives at the third optical port toward the first degree and guides the second optical signal that arrives at the second optical port toward the second degree.

A transmission method that is used by a transmission device for which a work path is established in a first degree and a protection path is established in a second degree, wherein the transmission device includes:

• a switch equipped with a plurality of optical ports,
• an optical signal generator, optically connected to a first optical port among the plurality of optical ports, and configured to generate an optical signal that is transmitted through the work path,
• a monitor light generator, optically connected to a second optical port among the plurality of optical ports, and configured to generate monitor light by using a wavelength tunable light source,
• a wavelength selective switch configured to select light with a designated wavelength from light guided toward the second degree, and
• a controller configured to control the wavelength selective switch, the transmission method comprising:
• controlling a wavelength of the monitor light generated by the monitor light generator such that the wavelength of the monitor light is substantially the same as a wavelength of the optical signal;
• controlling the switch to guide the optical signal that arrives at the first optical port toward the first degree and guide the monitor light that arrives at the second optical port toward the second degree;
• controlling the wavelength selective switch to select the monitor light guided from the switch and output the selected monitor light to the second degree;
• determining a state of the wavelength selective switch with respect to the wavelength of the monitor light in a manner such that a power of the monitor light output from the wavelength selective switch approaches a target level;
• and
• storing state data that represents the state of the wavelength selective switch in a memory.

A transmission system that includes a first transmission device and a second transmission device, a work path being established in a first transmission link and a protection path corresponding to the work path being established in a second transmission link between the first transmission device and the second transmission device, wherein

• the first transmission device includes
• a switch equipped with a plurality of optical ports,
• an optical signal generator, optically connected to a first optical port among the plurality of optical ports, and configured to generate an optical signal that is transmitted through the work path,
• a monitor light generator, optically connected to a second optical port among the plurality of optical ports, and configured to generate monitor light by using a wavelength tunable light source,
• a wavelength selective switch configured to select light with a designated wavelength from light guided toward the second transmission link, and
• a controller configured to control the wavelength selective switch, wherein
• the monitor light generator controls a wavelength of the monitor light such that the wavelength of the monitor light is substantially the same as a wavelength of the optical signal,
• the switch guides the optical signal that arrives at the first optical port toward the first transmission link and guides the monitor light that arrives at the second optical port toward the second transmission link,
• the wavelength selective switch selects the monitor light guided toward the second transmission link and outputs the selected monitor light to the second transmission link,
• the controller determines a state of the wavelength selective switch with respect to the wavelength of the monitor light in a manner such that a power of the monitor light output from the wavelength selective switch approaches a target level, and
• the controller stores state data that represents the state of the wavelength selective switch in a memory.