Electro-nanomechanically wavelength-tunable integrated-optical Bragg reflectors

Abstract

Electro-nanomechanical wavelength-tuning of integrated-optical (IO) Bragg reflectors is demonstrated at visible wave-lengths. Micromachined bridges or membranes are spanned over the waveguide as ‘effective-refractive-index shifting elements’ E in the region of a surface relief grating on the waveguide. Electrostatic forces cause elastic deflections of the elements E and, consequently, changes in the width of a typically 100–200 nm wide air gap between the element E and the waveguide. Thus the effective-refractive-index changes required for device operation are induced. The IO nanomechanical devices are fabricated with silicon technology; no electro-optic materials are required. The devices have response times of μs to ms. Potential applications as wavelength-tunable filters seem feasible.