Integrated nanomechanical motion detection by means of optical evanescent wave coupling

摘要

A central problem in the development of mechanical devices and systems is accurate and fast motion sensing. We demonstrate an integrated and near-field optical displacement sensing technique based on optical evanescent wave coupling. Exploiting the strong dependence of waveguide-to-waveguide coupling to changes in separation between waveguides we were able to detect in- and out-of-plane mechanical motions of a mechanical resonator. We have studied the sensitivity of the proposed motion detection technique with a 3D full-vectorial mode solver and make predictions on the attainable displacement detection limits based on a noise analysis. This work demonstrates both the feasibility and the effectiveness of integrating nanomechanical devices with photonic circuitry.