Performance Studies of High-Power Optical Parametric Oscillators Pumped by a Pulsed Fiber Laser

High-power optical parametric oscillators (OPOs), as mature radiation sources in mid-infrared (MIR), degenerate gradually with wavelength increase, mainly above 3700 nm. Using a periodically poled magnesium-oxide-doped lithium niobate (MgO:PPLN) as the nonlinear crystal, we build a high-power signal-resonant OPO pumped by ytterbium-doped fiber laser (YDFL). To improve the OPO's output power at similar to 3.8 & the parameters, such as the pump beam's waist diameter and location, the curvature radius of the output coupler and the length of MgO:PPLN, are discussed in detail. When pump power is 79 +/- 4 W with a repetition rate of 200 kHz, the OPO provides up to 8 +/- 0.4 W average power in beam quality with M-2 factors of similar to 1.84 and similar to 1.69 in the two axes. Under the highest output power, the center wavelength of the idler beam is 3768.4 nm with a full-width at half-maximum (FWHM) bandwidth of similar to 18.6 nm. When the output power reaches similar to 6.3 W, its power stability is 1.6% root mean square (RMS) over 7 h. Further analysis of the factors affecting OPO's performance and simple structure are critically essential for compact OPO prototypes with a capacity of high output power.