Modulated light source

A modulated light source comprising:

• an optical amplifier which includes a reflective film at one end;
• a light wavelength filter which has band-pass characteristics and modulates a transmission center wavelength;
• a light reflection mechanism which feeds back light having passed through the light wavelength filter to the optical amplifier and an optical resonator is formed between which and the reflective film;
• and
• a wavelength adjustment mechanism which adjusts the transmission center wavelength to coincide with a specific oscillation wavelength when light oscillation selectively occurs at the specific oscillation wavelength depending on the band-pass characteristics of the light wavelength filter,
• wherein the light wavelength filter is a ring modulator including a P-type doping region and an N-type doping region in a ring-state optical waveguide, and a modulation electrode applying a reverse bias voltage or a forward bias voltage between the P-type doping region and the N-type doping region in accordance with a modulation signal.