Abstract by Charles Bahr
Chemistry and Biochemistry
Heterogeneous Structures for Improved THz Generation
Terahertz spectroscopy is dependent upon reliable and powerful broadband THz sources. Compared to some other sources, organic crystals such as DSTMS and DAST generate THz with high efficiency through a non-linear optical process called optical rectification when induced with an ultrafast IR laser pulse. However, one disadvantage to using these crystals is their relatively high refractive indices at IR and THz frequencies in comparison to other sources. This large disparity between the index of the crystal and the index of air results in significant reflective loss of both IR pump intensity entering the crystal and THz exiting the crystal, thus leading to lower THz emission overall. To address this problem, we have designed a layered structure comprised of materials possessing intermediate refractive indices to the crystal and air, thus significantly reducing reflective loss. We tested our design on three crystal samples and measured a consistent increase in THz field output.