Frequency stabilization of the non-resonant wave of a continuous-wave singly resonant optical parametric oscillator

We present an experimental technique allowing to stabilize the frequency of the non-resonant wave in a singly resonant optical parametric oscillator (SRO) down to the kHz level, much below the pump frequency noise level. By comparing the frequency of the non-resonant wave with a reference cavity, the pump frequency noise is imposed to the frequency of the resonant wave and is thus subtracted from the frequency of the non-resonant wave. This permits the non-resonant wave obtained from such a SRO to be simultaneously powerful and frequency stable, which is usually impossible to obtain when the resonant wave frequency is stabilized.