Extreme tuning of microphotonic structures using optical forces

We show evidence of extreme tuning of micro-photonic resonances (31.4 nm) using optical gradient forces. We estimate the static mechanical displacements to be as large as 60 nm using mW level optical powers.

Large gradient optical forces can be achieved by exploring the fast decaying optical near field in micro photonic structures. Several groups have shown theoretically [1], [2] and experimentally [3]–[6] that such forces can modify both the static [3], [11] and dynamic behavior [4]–[7] of optical waveguides and cavities. However, in most cases, the optical force-induced resonance tuning is just few nanometers, limiting the potential of optomechanical tuning of these devices. This limited displacement may translate in poor performance when compared to other tuning techniques such as thermo-optic [7], carrier injection [8] and electrostatic-force actuation [9]. Hence, it is of great interest to pursue optomechanical devices which allow large tuning of their optical properties.