Parameter adjustable mid-infrared ultra-short pulse-burst laser around 2.94 μm

We report a parameter adjustable mid-infrared (MIR) ultra-short pulse-burst laser based on the difference frequency generation (DFG) within a periodically poled MgO:LiNbO₃ crystal. A uniform pulse laser at 1.03 μm with a sub-GHz repetition rate was first modulated into parameter adjustable burst modes, which subsequently served as the pump seed for the DFG process. A pulsed super-luminescent light emitting diode (SLED) was designed to synchronize with the pump burst duration and applied as the seed of signal wave. Synchronization was assured by utilizing separate channels of a single arbitrary waveform generator to control both the pulse picker and the SLED driver, thereby enabling the parameter-adjustment of the MIR burst. When the incident pump power was 18.8 W and the signal power was 2.51 W, a maximum MIR idler power of 1.33 W was obtained at 2941 nm with 1.5 MHz burst repetition rate and ∼ 60 ns width, corresponding to a total burst energy of 0.9 μJ. Such parameter adjustable MIR ultra-short pulse burst laser source is particularly promising for tissue ablation due to its high ablation efficiency, lower thermal damage and flexible operation mode.