High SNR, high repetition rate, compact, picosecond, mid-infrared optical parametric oscillator pumped synchronously by a harmonic mode-locked fiber laser

This study proposes and demonstrates a high-performance picosecond mid-infrared optical parametric oscillator (OPO) based on harmonic mode-locked erbium-doped fiber laser synchronous pumping. The OPO exhibits unparalleled advantages including a compact structure, high repetition rate, excellent stability, and high signal-to-noise ratio (SNR). The OPO output pulse maintains a high repetition rate of 0.8 GHz while exhibiting highly uniform amplitude and a high SNR of 52 dB at 2.3 µm, and its cavity length is only 16 cm. The signal light wavelength is tunable within the range of 2.3-2.46 µm, while the idler light can be tuned within 4.18-4.74 µm. When the pump power is 4 W, the OPO delivers 120 mW of idler light power at 4.18 µm. This work provides what we believe to be a novel and effective solution for realizing ultrafast tunable lasers in the mid-infrared with a high repetition rate and a high SNR, which is expected to play an important role in the fields of spectroscopy and medicine.