Patent ID: 7215687

Claim:
An optical fiber laser apparatus comprising: an excitation light source for outputting light of a given wavelength; a first optical fiber having an end connected to an output of the excitation light source, and having a core doped with a rare earth substance to generate light of a plurality of wavelengths including light of a first wavelength by up-conversion from the output light; a first resonator including first and second mirrors provided on both ends of the first optical fiber, respectively, the first resonator selecting the first wavelength light out of the light of the wavelengths resonating in the first optical fiber between the first and the second mirrors to output via the second mirror; and a second optical fiber having an end connected to the other end of the first optical fiber, the second optical fiber amplifying an output of the first wavelength light incident from the first resonator, wherein light of wavelengths other than the first wavelength light comprises light of a second wavelength having higher gain per length of the optical fiber than the first wavelength light, wherein the first and second mirrors have higher reflexivity for the first wavelength light than for the second wavelength light, and wherein the first optical fiber has a length set such that the first wavelength light oscillates preferentially over the second wavelength light.