Radiation-pressure-induced mechano-optical bistability

We suggest and analyze a new radiation-pressure-induced bistability: A planar waveguide is suspended to swing as a torsional pendulum. A laser beam is coupled into the waveguide by a grating input coupler at one end of the waveguide and is outcoupled at the other end. The incoupling efficiency has a sharp angular resonance. When the pendulum is initially detuned from resonance, the torque exerted by the radiation pressure tends to drive it into resonance. The torque is proportional to the incoupling efficiency; therefore it depends on the angular position of the pendulum. This feedback leads to the mechano-optical bistability.