Wavelength-Locked 878.6 nm In-Band Pumped Intra-Cavity 2.1 μm Optical Parametric Oscillator* *Supported by the National Natural Science Foundation of China under Grant No 61505013, the Postdoctoral Science Foundation of China under Grant No 2016M591466, and the Science and Technology Department Project of Jilin Province under Grant Nos 20170204046GX and 20190101004JH.

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We report herein a high-power folded intra-cavity 2.1 μm optical parametric oscillator (ICOPO) which is the first example of an ICOPO that utilizes a wavelength-locked 878.6 nm in-band pumped Nd:YVO4 laser as the pump source. The thermal effect of PPMgLN crystal and the divergence angle of the incident laser are considered comprehensively to determine the 2128 nm degenerate temperature. In the experiment, the functions of different output coupler transmittances and different repetition rates on the parametric laser output power are studied, respectively. The temperature versus parametric laser output power in an in-band pumped non-wavelength-locked 880 nm laser diode (LD) and in a wavelength-locked 878.6 nm LD is compared. A maximum output power of 5.87 W is obtained at the pump power of 56.9 W when the repetition rate is 80 kHz. The corresponding conversion efficiency is 14.55%, with a linewidth of 73.65 nm and pulse width of 3.62 ns. The wavelength-locked 878.6 nm LD in-band pumping technology can stabilize the 2.1 μm laser output power of Nd:YVO4 crystal effectively in the environment of intense temperature change.