Modulation function with a light source device and a driving method thereof

Periodically has a wavelength conversion module comprising a nonlinear optical material nonlinear constants have a modulated structure (75), WDM coupler excitation light from different semiconductor laser light source wavelength to the optical waveguide (71) and (72) the difference frequency generated by incident multiplexes by (74), or a modulation function with a light source device for outputting a sum frequency, the semiconductor laser light source (72) has a built-in diffraction grating, a semiconductor laser light source (71) includes means for modulating the output beam emitted from the semiconductor laser, to connect FBG (73) to the outside with a narrow reflection band than the resonance wavelength spacing determined by the device length of the semiconductor laser, it is modulated modulation function with a light source apparatus characterized by inputting the output to the FBG (73).