Spatiotemporal control of two-color terahertz generation
T. T. Simpson, J. J. Pigeon, M. V. Ambat, Kyle G. Miller, D. Ramsey, Kathleen Weichman, D. H. Froula, J. P. Palastro
Abstract
A laser pulse composed of a fundamental and properly phased second harmonic exhibits an asymmetric electric field that can drive a time-dependent current of photoionized electrons. The current produces an ultrashort burst of terahertz (THz) radiation. When driven by a conventional laser pulse, the THz radiation is emitted into a cone with an angle determined by the dispersion of the medium. Here we demonstrate that the programmable-velocity intensity peak of a spatiotemporally structured, two-color laser pulse can be used to control the emission angle, focal spot, and spectrum of the THz radiation. Of particular interest for applications, a structured pulse with a subluminal intensity peak can drive highly focusable, on-axis THz radiation. Published by the American Physical Society 2024