Ultra-low-energy non-volatile phase shifters

An integrated photonic device, comprising:

• a waveguide having a top surface, a bottom surface and a pair of side surfaces, the waveguide configured to guide radiation having one or more wavelengths within a wavelength band,
• a heat-actuable phase change material (PCM) optically coupled to the waveguide, and
• a heater disposed between the waveguide and the PCM, the heater having a two-dimensional material layer at least partially disposed above the top surface of the waveguide and configured for application of a voltage pulse thereto for causing heating thereof, and
• a first electrically insulating spacer layer separating said two-dimensional material layer from the top surface of the waveguide,
• wherein said two-dimensional material layer is in thermal communication with the PCM such that heat transfer from the two-dimensional material layer, when heated, to the PCM causes the PCM to undergo a material phase transition between a crystalline state and an amorphous state, thereby causing a change in a refractive index of the PCM and a resultant change in at least one of a phase and transmission of an electromagnetic wave propagating through the waveguide.