An Infrared Picosecond Optical Parametric Oscillator for Polymer Ablation

Abstract

The development of an infrared optical parametric oscillator based on Magnesium Oxide doped Periodically Poled Lithium Niobate (MgO:PPLN) is described. The OPO is synchronously pumped by a high average power, picosecond, Nd:YVO4 mode-locked laser operating at 1064nm. The OPO generates signal and idler radiation at wavelengths centered at 1550nm and 3.4µm respectively. The OPO is singly resonant at the the signal wavelength. The multiple QPM grating periods and temperature control imposed upon the PPLN crystal afford a broad tuning range of the OPO output. The signal is tunable from 1450-1700nm, corresponding to an idler tuning range of 2.8-4.0µm. Pumping the OPO at 10W yielded 1.5W of extracted idler power at 3.3µm. The OPO is intended as a light source for pulsed laser ablation of polymers. Previous demonstrations of pulsed laser polymer ablation used a Free Electron Laser as the light source. The OPO was successfully used to evaporate polymers, although the physical mechanism is uncertain. Further development of this, or similar devices offers a flexible, and more accessible alternative to a FEL for polymer ablation.