High Repetition Rate, 4 µm Mid-Infrared Generation with Periodically Poled Magnesium-Oxide-Doped Lithium Niobate Based Optical Parametric Oscillator Pumped by Fiber Laser

We recently experimentally demonstrated a high-power, high-repetition-rate mid-infrared (mid-IR) radiation at 4.0 µm, based on the fiber-laser pumped optical-parametric-oscillator (OPO) configuration. To ensure the excellent characteristics of the OPO output, the master oscillator power amplifier (MOPA) structure fiber laser was developed as the pump source and the homemade periodically poled magnesium-oxide-doped lithium niobate (PPMgLN) crystal (60 mm in length) was employed in the oscillator. Under the pump power of 18.5 W, the maximum 2.03 W average power of 4.0 µm idler laser was finally achieved at a high repetition rate of 200 kHz. In addition, the overall OPO output power of 8.8 W was also realized, corresponding to the total conversion efficiency as high as 48%.