A wavelength tunable device for operating on at least a portion of energy propagating through a waveguide is disclosed. The wavelength tunable device includes an upper cladding and a lower cladding having a core substantially disposed there between and suitable for optically coupling to the waveguide, a pattern of nanostructures positioned substantially on the upper cladding distal to the core so as to define a reflectivity for energy propagating through the waveguide, and, a movable membrane aligned with the pattern of nanostructures so as to at least partially define a gap there between. This gap may be selectively controlled upon actuation of the movable membrane so as to cause a corresponding change in the reflectivity.