It is possible to utilize changes in the complex effective refractive index caused by bringing a metal membrane in close proximity to the core of an optical waveguide to form many devices. The invention described herein provides structures and processes that do so, the structure comprising a substrate, a lower cladding, a waveguide core, a removable upper cladding which supports a metal membrane, and an electrode for deflecting said membrane.Switchable devices using this structure include, but are not limited to, polarizers, mode converters, optical switches, Bragg devices, directional couplers and channel waveguides.