Highly nonlinear photocurrents

In the photovoltaic effect a single light quanta (photon) is absorbed by a material, exciting an electron to a higher band, and potentially generating a photocurrent if the sample is gated by external voltage, or has some broken symmetry. We are interested in analogues of this effect in the multi-photon and highly-nonlinear regime. Here photocurrents can be generated by extremely short few-cycle pulses, and even in inversion-symmetric materials if the symmetries of the laser pulse itself are pre-engineered. 

We attempt to uncover the attosecond nature of this process and its connection to electron dynamics inside the solid, develop spectroscopy techniques for all-optical detection of currents, and utilizing current measurements for ultrafast spectroscopy of various material properties and phenomena.