Light source device

A light source device comprising:

• a fiber laser including an excitation light source and configured to output pulsed light generated according to excitation light from the excitation light source;
• a fiber amplifier configured to receive the pulsed light output from the fiber laser, amplify the pulsed light, and output the amplified pulsed light;
• a wavelength shift fiber configured to receive the pulsed light output from the fiber amplifier, shift a wavelength of the pulsed light, and output the pulsed light;
• an output fiber configured to receive the pulsed light output from the wavelength shift fiber, and output the pulsed light to an outside;
• a light detection element configured to detect, in the output fiber, the pulsed light having passed through at least the wavelength shift fiber;
• and
• a control unit configured to control a drive current of the excitation light source,
• wherein the light detection element detects light in a partial wavelength band of the pulsed light having passed through the wavelength shift fiber, and
• the control unit executes, by changing the drive current of the excitation light source in one direction according to an output value of the light detection element, acquisition processing of acquiring a specified current value of the drive current at which the output value of the light detection element is greater than or equal to a specified value.