(a) Schematic and SEM images of bi-layer PhC (Force for symmetric mode is depicted). (b) photonic bandedge
modes in the bi-layer PhC. (c) power dependence of reflectance spectra for the symmetric mode. (d) fundamental
vibration mode with odd symmetry to modulate optical mode. (e) RF spectra of reflected light.


Ultralarge Optomechanical Coupling in a Bi-layer Photonic Crystal

We realized bi-layer photonic crystal (PhC) embedding a thin air gap and observed its optomechanical coupling phenomena. Two InP PhC slabs with thickness of 200 nm were separated by an air gap with thickness of 200 nm. We could observe large shift of bandedge mode in reflectance spectra. This can be explained by displacement of the PhC slabs by huge radiation force, resulting from strong optomechanical coupling. Such strong optomechanical coupling also allowed the tiny Brownian motion of slabs to modulate optical resonant mode, which could be observed as a peak in the RF spectra of the reflected light beam. (Page 42)