System and method embodiments are provided for a thermo-optic switch with thermally isolated and heat restricting pillars. The embodiments enable increased integration density in photonic integrated chips (PICs), reduced power consumption, improved switching speed, and increased chip lifetime. In an embodiment, an optical waveguide; a resistive heater in thermal contact with a surface of the optical waveguide; and a plurality of heat flow restricting pillars connected to the sides of the optical waveguide and supporting the optical waveguide such that the optical waveguide is substantially thermally isolated from a substrate below the optical waveguide by a gap formed between the optical waveguide and the substrate, and wherein the pillars restrict heat flow from the optical waveguide to a supporting structure that supports the pillars.