It is important to develop continuously tunable light sources in the IR region, since the infra-red light can be utilized for a number of applications, such as ranging and detection. An attempt was made to realize an optical parametric oscillation (OPO) using highly nonlinear organic crystal, MMONS.
An MMONS sample was prepared so that the pump beam could be propagated in the direction of θ=73°, φ=0° at normal incidence. The cavity of OPO was formed by two mirrors which have reflectances of R＞99% and R~80%, respectively, for the wavelengths of 950~1050nm. A cylindrical lens (f=50cm) was used to overcome the relatively large walk-off effect for the signal beam. The MMONS OPO was pumped by the pulsed beam of 9ns at 600nm wavelengths. The signal beam was detected by a Ge photodiode and then displayed on an oscilloscope.
Also phase-matching (PM) angles, effective nonlinear optical coefficient, and walk-off angles were calculated for type Ⅲ PM when the pump wavelength was 600nm. Optical parametric oscillation was achieved by angle tuning in the spectral range of 1.4㎛ to 1.7㎛ and 0.85㎛ to 1.05㎛ for the signal and idler waves, respectively. It was found that the experimental data agreed very well with the theoretical calculation.
