Thanks to the generous support of Dr. Richard Williams, I am beginning some work with his Ultrafast Laser Spectroscopy group at Wake Forest University.
Work has been done at Wake Forest University using sub-picosecond absorption spectroscopy following band-gap excitation of alkali halide crystals to study defect formation on very short time scales. We have recently worked to optimize the state-of-the-art system utilizing a Ti-sapphire laser along with a two-stage chirped regenerative amplifier to create 855 nm (1.45 eV) pulses with a 130 fs duration and a pulse energy of up to 5 mJ. We are able to study defect formation in materials which have not been studied with this time resolution before. The recent addition of the second stage to the amplifier will allow us to study defect formation in materials that have never been studied due to relatively large band-gap. It has allowed us to look at more wider band-gap materials since we can now get more photons, hence larger signal, in the 3rd and 4th harmonic generation. The direction of the study is currently to study some technologically relevant materials: lithium niobate, KTP (nonlinear crystals used in optical applications) and AgCl, and to start a systematic study of the oxides.