Abstract

Tunable and high power ultra-short pulses in mid- and far-infrared (IR) spectral region are required for pump-probe spectroscopy of molecular vibrational structures and the low-energy excitations in solid state materials. Nonlinear optical frequency down conversion has been demonstrated for mid-IR short-pulse generation [1]. Among inorganic and organic materials, an organic nonlinear optical crystal DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate), which consists of a stilbazolium cation and a tosylate anion, is quite efficient for the frequency conversion down to THz wave region because of large nonlinear optical coefficients and relatively small absorption [2, 3]. In the present paper, we report the generation of mid-IR short-pulse in spectral range of 10 ~ 40 μm (7.5 ~ 30 THz) using DAST crystals.

© 2009 IEEE