Optical transmission device, transmission system, and control method for transmission system

An optical transmission device comprising:

• an output branching unit that multiplexes an added main signal and dummy light and outputs the multiplexed signal to an optical transmission line;
• a wavelength adjustment unit that adjusts a wavelength band of the dummy light;
• a signal detection unit that inputs an optical signal to be output by the output branching unit, detects a wavelength band of an added main signal, and outputs a detection result;
• and
• a control unit that controls the wavelength adjustment unit according to a detection result of the signal detection unit, wherein
• the output branching unit selects the wavelength band of the added main signal, outputs a signal of the selected wavelength band to the signal detection unit, and outputs the signal of the selected wavelength band to the optical transmission line in response to the wavelength adjustment unit controlling the wavelength band of the dummy light.