| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to solve the problem accompanying the occurrence of a transverse mode mainly occurring in a nonlinear optical crystal of an optical system for executing wavelength conversion and to obtain stable output, such as stable wavelength conversion output, by irradiating this nonlinear optical crystal with UV light of a wavelength below a specific value. SOLUTION: The nonlinear optical crystal 5 of the optical system for executing the wavelength conversion by using an external resonator is irradiated with pulse UV light of a wavelength below 400 nm. An effect may be obtd. if an adequate irradiation quantity is imparted to the crystal regardless of pulse shapes. Favorable results may be obtained by applying this constitution to the case whereβ-BaB2O4 (BBO) is used as the nonlinear optical crystal 5 and by applying the constitution to the case where UV light of a wavelength 266 nm is used. Namely, a basic wavelength 7 (wavelength 532 nm) is made incident and output is amplified between mirrors 1 and 4. The intensified basic wave is converted to second harmonic 8 (wavelength 266 nm) by the BBO 5 previously irradiated with the UV light.</p> |
