Patent ID: 7773643
Filing Date: 2010-08-10
Classification: G02F

Abstract:
1. A laser light generating apparatus, comprising: a laser light source; a first external resonator and a second external resonator disposed at a stage succeeding the first external resonator; a phase-modulator disposed on an optical path between the laser light source and the first external resonator, the phase-modulator being applied with a modulation signal; a signal generating unit configured to generate the modulation signal applied to the phase-modulator; first and second nonlinear optical elements disposed in the first and second external resonators, respectively, configured to implement a wavelength conversion of a laser light incident on each of the first and second external resonators; an optical path length varying means for varying an optical path length of each of the first and second external resonators; at least one photodetector configured to receive the laser light emerging from each of the first and second external resonators; and a control circuit having a negative feedback arrangement configured to acquire at least one detection signal received by the at least one photodetector and the modulation signal to thereby obtain error signals for each of the first and second external resonators, and configured to control the optical path length varying means using the error signals according to an FM sideband method, wherein the first and second external resonators are each held simultaneously in a resonance state by setting a frequency of the modulation signal to be equal to a value which is obtained so that S/N ratios of the error signal for each of the first and second external resonators may be averaged, and by controlling the optical path length of each of the first and second external resonators by the control circuit, wherein a frequency of sidebands generated by a phase modulation of the laser light is set in a first range of from 0.5 to 2 times a first frequency range corresponding to a transmission width, in terms of half width at half height, of the first external resonator centered at a resonance frequency of the first external resonator, and simultaneously in a second range of at least 0.5 times a second frequency range corresponding to the transmission width of the second external resonator centered at the resonance frequency of the first external resonator.