Patent ID: 7801186

Claim:
A light source comprising: a semiconductor pumping laser that outputs a pumping laser light; a pumping-light waveguide that guides the pumping laser light output from the semiconductor pumping laser; an amplified-light waveguide that is connected to the pumping-light waveguide, and that is doped with an amplification medium that is pumped by the pumping laser light so that a spontaneous emission light in a desired wavelength band is generated; an output-light waveguide that guides the spontaneous emission light output from the amplified-light waveguide; a spatial coupling unit provided between the amplified-light waveguide and the output-light waveguide, the spatial coupling unit including a wavelength selecting element that selectively transmits a light having a desired wavelength band out of the spontaneous emission light, a lens unit that couples the spontaneous emission light to the wavelength selecting element, and a polarizer that transmits a light of the spontaneous emission light with a predetermined polarization; an input-side light reflecting unit that is provided between the semiconductor pumping laser and the amplified-light waveguide; and an output-side light reflecting unit that is formed on an output side of the spatial coupling unit, wherein the input-side light reflecting unit and the output-side light reflecting unit form a laser resonator that includes the amplified-light waveguide and the spatial coupling unit, and the output-side light reflecting unit is a fiber Bragg grating formed on the output-light waveguide, and that selectively reflects a light in a wavelength band including a transmission wavelength of the wavelength selecting element.