Optical forces and optoelastic instability

This letter studies the nonlinear behavior of a nano-opto-mechanical actuator, consisting of a free-standing arc in a ring resonator that is coupled to a bus waveguide through evanescent waves. The arc deflects when a control light of a fixed wavelength and optical power is pumped into the bus waveguide, while the amount of deflection is monitored by measuring the transmission spectrum of a broadband probe light. This nano-actuator achieves a maximal deflection of 43.1 nm, with a resolution of 0.28 nm. The optical force is a nonlinear function of the deflection of the arc, leading to “pull-back” instability when the control light is red-tuned. This instability is studied by a combination of experiment and modeling. Potential applications of the nano-actuator include bio-nano-motor, optical switches and optomechanical memories.