Development of an all-solid-state pulsed picosecond laser system for nonlinear spectroscopy

We present the state-of-the-art of the development of an all-solid-state short and fine linewidth pulsed laser systems for high sensitivity sum-frequency generation (SFG) spectroscopy. Fine linewidth picosecond pulses, tunable in the infrared and visible spectral ranges, are generated by a Nd:YAG laser mode-locked using a frequency-doubling nonlinear mirror in combination with a nonlinear absorber. Continuous tunability in the visible and infrared spectral ranges is achieved by building optical parametric oscillators (OPOs) around the appropriate nonlinear crystals. A single conversion stage based on a LiNbO 3 and an AgGaS 2 crystals is used for mid-infrared tunability, whereas a two-step conversion process using a KTP-based OPO followed by a CdSe crystal is used for wavelength tuning in the far-infrared. Tunability in the visible is insured by pumping a BBO-based OPO with the third harmonic of the Nd:YAG wavelength. The fine spectral resolution is obtained by inserting an etalon plate inside the OPO cavity which thanks to an elaborated rotation-control algorithm provides reliable and practical tuning in comparison with grating-based systems. These short and fine laser pulses are suitable for use for SFG spectroscopy.