Optical transmission device

An optical transmission device comprising:

• a first wavelength selective switch for a first wavelength band with a shorter wavelength than a second wavelength band;
• a first wavelength selective switch controller configured to control an output power of the first wavelength selective switch;
• a first variable optical attenuator coupled to an output of the first wavelength selective switch and configured to control the output power of the first wavelength selective switch;
• a first variable optical attenuator controller configured to control the first variable optical attenuator;
• a second wavelength selective switch for the second wavelength band;
• a second wavelength selective switch controller configured to control an output power of the second wavelength selective switch;
• a second variable optical attenuator coupled to an output of the second wavelength selective switch and configured to control the output power of the second wavelength selective switch;
• a second variable optical attenuator controller configured to control the second variable optical attenuator;
• and
• a coupler configured to multiplex an output of the first variable optical attenuator and an output of the second variable optical attenuator,
• the first variable optical attenuator controller, when the first wavelength band is added to or removed from the optical transmission device, controls the first variable optical attenuator at a slower speed than a control speed of the second wavelength selective switch, and the second variable optical attenuator controller, when the second wavelength band is added to or removed from the optical transmission device, controls the second variable optical attenuator at a slower speed than a control speed of the first wavelength selective switch.