Patent ID: 7791790

Claim:
A wavelength converter comprising: a fiber including a laser active substance, the fiber being formed with a first fiber grating and a second fiber grating, wherein the first fiber grating and the second fiber grating are embedded in the fiber; a laser light source that allows pumping light to be incident on the fiber; a laser resonator formed by optically connecting the fiber and the laser light source; and a wavelength conversion element that converts the fundamental wave of a laser beam emitted from the laser resonator into a higher harmonic wave, wherein the first fiber grating is arranged between the laser light source and the second fiber grating, and the second fiber grating is arranged between the first fiber grating and the wavelength conversion element; wherein the fiber absorbs a part of an output of the fundamental wave or the pumping light, and heats the second fiber grating, and wherein the temperature of the second fiber grating is adjusted in accordance with an output of the higher harmonic wave outputted from the wavelength conversion element.