Single-frequency pump-enhanced monolithic MgO:PPLN optical parametric oscillator and vortex beam generation

We present a pump-enhanced monolithic optical parametric oscillator (OPO) capable of W-level single-frequency mid-infrared (MIR) output and optical vortex beam generation. Utilizing a Gaussian pump and a pump-enhanced cavity design, the monolithic OPO achieved a maximum idler output power of 1.4 W and a tuning range of 3016-3200 nm. The OPO maintained single-frequency operation with a linewidth of 218 kHz at W-level output. Due to thermal effects, the OPO had an RMS power stability of 0.7% over one hour and long-term mode-hop-free performance. When pumped with an optical vortex, orbital angular momentum could be effectively transferred to the idler or signal beam, achieving maximum idler or signal vortex powers of 0.6 W or 1.8 W, respectively. Additionally, idler vortex generation was demonstrated across the entire tuning range.