Self-induced backaction in optical waveguides

Abstract

In this paper, we study the backaction effect on the force exerted upon Rayleigh particles in guided structures. We show that the backaction becomes stronger as the group velocity of the guided modes is decreased, which is not unexpected since the fall of group velocity increases the interaction time between the particle and the electromagnetic field. Interestingly, the sign of the group velocity affects the pushing and pulling nature of the exerted electromagnetic force. We specifically investigate the case of a single mode optical waveguide both in the propagating and evanescent regimes, and show that the backaction enables us to enhance the ratio of the potential depth to the trapping intensity, and thereby can be a beneficial tool for nondestructive trapping of small nanoparticles. We further show that backaction can induce some resonances in the optical force in the evanescent regime. These resonances can be employed for sorting of nanoparticles.