Ultrafast dynamic wavefront control for light redistribution via optical Kerr effect

Abstract

An approach for ultrafast dynamic light redistribution by wavefront control via the optical Kerr effect is proposed. In this approach, an intense pump laser with a temporal profile of a Gaussian pulse train is incident in a bulk Kerr medium or a fused silicon cell filled with liquid Kerr medium to induce a spatiotemporal refractive index of the medium, and meanwhile a signal laser is propagating through the medium. Due to the spatiotemporal refractive index of the medium induced by the pump laser, the wavefront of the signal laser is modulated in both spatial and temporal domains. As a result, the Kerr medium functions as a moving microlens array for the pump laser perpendicular to the signal laser, or as a varifocal lens for the pump laser oblique to the signal laser at a small angle. Consequently, the light field in the focal region can be redistributed rapidly due to the spatiotemporal wavefront modulation to the signal laser by the Kerr medium. Moreover, the response of the optical Kerr effect is on the order of sub-picoseconds, which enables the light redistribution period of the signal laser to be below a few picoseconds. Results indicate that this approach can effectively shape the wavefront of the laser, redistribute the light field in the focal zone, and finally improve the irradiation characteristics of laser beams.