A Stabilized Doubly Resonant OPO for THz Applications

Strong tailored two- and three-color optical waveshapes can be useful for effective generation of light at very high (XUV) and very low (THz) frequencies [1] , [2] . In particular, for generation of THz radiation, strong and stable asymmetric temporal-waveshapes are needed. Phase locked doubly-resonant optical parametric oscillators (DROPOs) can contribute with intensities high enough for this goal. In this work, we stabilize our degenerate DROPO by using a locking scheme which utilizes monitoring of a "spurious"-sum-frequency product (SFG) of signal and pump in the amplifier crystal – a method proposed very recently in [3] . In our experiment, we synchronously pump the DROPO by a home-built Yb:YAG Kerr-lens mode-locked thin-disk laser, emitting pulses at a wavelength of 1030 nm with a pulse duration of 250 fs, 20 W output power and 33 MHz repetition rate.