1.8-μm MgO: PPLN optical parametric oscillator pumped by Nd: YVO4/YVO4 2nd-Stokes Raman laser

Abstract An efficient MgO: PPLN singly resonant optical parametric oscillator (SROPO) pumped by a Nd: YVO4/YVO4 2nd-Stokes Raman laser at 1313 nm was demonstrated. The maximum conversion efficiency of 54.8% was obtained at the pump power of 1.16 W, which was higher than that of the OPO pumped by 1st-Stokes Raman laser at 1176 nm, due to the better beam quality, narrower line width and pulse width of the 2nd-Stokes Raman laser. The maximum output power of 1.57 W at 1855.5 nm with the pulse repetition frequency (PRF) of 40 kHz was achieved under the pump power of 4 W. The corresponding conversion efficiency was 39.7%, with the pulse width of 2.53 ns, linewidth of 0.45 nm, and M2 of 1.87. Meanwhile, with the crystal period ranging from 27.91 to 29.98 μm, the tuning range of signal wave was 1778.6–1861.8 nm.