Frequency-agile kilohertz repetition-rate optical parametric oscillator based on periodically poled lithium niobate.

We report kilohertz repetition-rate pulse-to-pulse wavelength tuning from 3.22 to 3.7 mum in a periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO). Rapid tuning over 400 cm(-1) with random wavelength accessibility is achieved by rotation of the pump beam angle by no more than 24 mrad in the PPLN crystal by use of an acousto-optic beam deflector. Over the entire tuning range, a near-transform-limited OPO bandwidth can be obtained by means of injection seeding with a single-frequency 1.5-mum laser diode. The frequency agility, high repetition rate, and narrow bandwidth of this mid-IR PPLN OPO make it well suited as a lidar transmitter source.