Radiation Torque Exerted on a Rotating Sphere in a Focused Gaussian Laser Beam: First-Order Correction in Angular Velocities

We investigate the radiation torque exerted on a rotating dielectric sphere in a focused Gaussian beam. In the (inertial) laboratory frame we solve the relativistic scattering problem for the Gaussian beam incident on a rotating sphere by including correction terms of up to first-order in angular velocities. We then derive the analytical formulas of the radiation torque within the framework of a scattering theory and discuss the derived results in comparison with our earlier works for a stationary sphere. Numerical results show that the ratio of the first-order correction to the zeroth-order torque is about 0.2×10 -2 at the highest rotational frequency.