Waveguides and methods of fabrication thereof are presented. A representative waveguide includes a waveguide core and a cladding layer, where the cladding layer surrounds the waveguide core. The waveguide core and cladding can be made of a host material having a plurality of nano-pores, wherein the nano-pores include a sacrificial material, and the sacrificial material can be selectively decomposed in both the core and cladding layers to form a plurality of nano air-gaps.