Sub-kHz linewidth intracavity VECSEL-pumped OPO

We report low noise and narrow linewidth performance of an actively stabilized optical parametric oscillator, intracavity-pumped by a visible AlGaInP-based vertical-external-cavity surface-emitting laser (VECSEL). Under dual-locking conditions, where the VECSEL and intracavity resonant idler are stabilized using the Pound–Drever–Hall and side-of-fringe locking techniques, respectively, narrow linewidths of 6.21(1) kHz (VECSEL) and 151(1) Hz (idler) are achieved for integration times as long as 4 s, illustrating the transfer of noise from the VECSEL fundamental to the OPO non-resonant signal. In this regime, the relative intensity noise of all three interacting waves is <−120 dBc/Hz for all frequencies above 1 kHz, indicating that this coherent laser system is well-suited for quantum optics experiments, potentially those involving squeezed light generation.