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.