Threshold Calculations for an Optical Parametric Oscillator Employing a Hemispherical Resonator

Abstract

A calculation of optical parametric oscillator threshold has been carried out for an oscillator which employs a hemispherical resonator. The analysis considers the effects of focusing and double refraction, and makes possible the calculation of threshold as a function of the focusing parameter ξ and double-refraction parameter B. The analysis is similar to that carried out by Boyd and Kleinman for a different class of optical resonators. Their analysis assumes that the pump beam is centered (longitudinally) with respect to the focus of the oscillator pump beam. In a hemispherical resonator, however, only half of the pump-beam focal region can be utilized because of the resonator configuration. As one would expect, oscillator threshold is higher for the hemispherical case than for the Boyd and Kleinman case. However, the increase is at most a factor of 2 (when beam walkoff is absent, i.e., when B=0), and gradually goes to unity as B increases in size. Thus by using a hemispherical resonator in an optical parametric oscillator, one gains experimental convenience at the expense of a slight increase in oscillator threshold.