Modulation-free control of a continuous-wave second-harmonic generator

Abstract

We present results for continuous-wave second-harmonic generation of 532 nm light in an external cavity locked using a spatial mode interference technique. This technique does not require frequency modulation and thus yields a clean second-harmonic spectrum devoid of modulation sidebands. The performance is compared with the same system controlled by Pound-Drever-Hall locking. Both techniques achieved the same maximum output power with comparable stability which is predominantly limited by fluctuations in the pump power and the nonlinear crystal temperature.