Nanoscale Ultrafast Spectroscopy

Artist's depiction of molecular-scale THz spectroscopy.

LaAlO3/SrTiO3 (LAO/STO) nanojunctions enable a new type of molecular-scale spectroscopy which combines the high temporal resolution of ultrafast optical sources with electronic structures which can be programmed with extreme nanoscale precision.  Our unique optical platform can harness the intrinsically large third-order nonlinear susceptibility of STO by converting it to a local second-order susceptibility at a nanoscale junction.  This nanoscale nonlinearity can be used to generate broadband THz emission at 10 nm scales, and has been demonstrated to produce strong optical extinction features in graphene and graphene nanoribbons.  This system is capable of interrogating a wide range of materials by placing them on the LAO/STO canvas, and "writing" a nanoscale junction centered around a single molecule.