Abstract
While conventional Raman Spectroscopy (RS) has predominately used fixed wavelength cw lasers,
advanced Raman spectroscopic techniques such as Stimulated Raman and some types of Raman Imaging
typically need pulsed lasers with sufficient energy to induce the Raman process. In addition, pulsed lasers
are beneficial for the following Raman techniques: Time Resolved Raman (TRR), Resonance Raman (RR),
or non linear Raman techniques, such as Coherent anti-Stokes Raman spectroscopy (CARS). Here the
naturally narrower linewidth of a ns pulse width laser is advantageous to a broader linewidth ultrafast
pulsed laser.
In this paper, we report on the development of a compact, highly efficient, high power solid-state
Ti: Sapphire laser ideally suited for many Raman spectroscopic techniques. This laser produces nanosecond
pulses at kHz repetition rates with a tunable output wavelength from ~1 micron to ~200 nm and pulse
energies up to 1 mJ. The narrow bandwidth of this laser (<0.1cm-1) is ideally suited for applications such as
Laser-induced fluorescence (LIF) measurement of OH free-radicals concentrations, atmospheric LIDAR
and Raman spectroscopy.
New KBBF and RBBF deep ultraviolet (DUV) and vacuum ultraviolet (VUV) crystals are now
available that enable direct doubling of the SHG output of these tunable Ti: Sapphire lasers to directly
achieve wavelengths as short as 175 nm without the need to generate the 3rd harmonic and utilize frequency
mixing. This results in a highly efficient output in the DUV/VUV, enabling improved signal to noise ratios
(S/N) in these previously difficult wavelength regions. Photonics Industries has recently achieved a few
mW of power at 193nm with such direct doubling crystals.
