Characteristics of a high-power picosecond mid-IR parametric generator/amplifier tunable between 1.5 and 3.2 μm

The usage of coherent radiation in the mid-infrared (mid-IR) wavelength range (2 – 8 μm) covers a wide spectrum of applications in many different fields. To satisfy the demand for a high-power, picosecond mid-IR source, we are developing an optical parametric system tunable between 1.45 and 3.5 μm in wavelength. The pumping of the system is provided by an in-house built Yb:YAG thin-disk laser, delivering 80 W of average power at 93 kHz pulse repetition rate, 1030 nm wavelength and ~1.3 ps pulse duration. The optical parametric system consists of a double-pass optical parametric generator (OPG) based on a periodically poled lithium niobate. By utilizing four periods of poling and temperature tuning, wavelength tunability range is from 1.45 to 3.5 μm. Maximum signal output power was around 85 mW at 1850 nm wavelength at 2 W pump power. Subsequent amplification of the signal generated in the OPG stage takes place in an optical parametric amplifier (OPA), which consists of a pair of walk-off compensating KTA crystals, pumped by up to 50 W average power. Maximum output signal and idler sum power after the OPA stage was 8.4 W. The wavelength tunability of the amplifier spans from 1.5 to 3.2 μm. Further increase in the tunability range as well as gapfree tuning is currently crystal mount-limited.