Terahertz oscillatory radiation torque at the microscale

Abstract

We propose and demonstrate numerically, through time-domain simulations of Maxwell’s equations, a method to generate an oscillatory radiation torque of pN ⋅ μm strength and sub-picosecond period of oscillation. The approach is based on the change of light’s instantaneous angular momentum as it resonantly excites a micro-cylindrical rod possessing an azimuthally varying continuous refractive index profile. The torque amplitude and its oscillation period can be controlled by a proper change in the rod’s size and in light’s frequency and electric field amplitude.