Optical Devices with Phase-Change Materials

A method of testing a photonic integrated circuit comprising a first waveguide evanescently coupled to a second waveguide coated with a layer of phase-change material reversibly switchable, at least in part, between an amorphous state with a first refractive index and a crystalline state with a second refractive index higher than the first refractive index by at least 0.1, the method comprising:

• coupling light into the first waveguide;
• switching the layer of phase-change material, at least in part, between the amorphous state and the crystalline state to increase a coupling ratio from the first waveguide to the second waveguide;
• detecting light coupled into the second waveguide from the first waveguide;
• and
• switching the layer of phase-change material, at least in part, between the amorphous state and the crystalline state to decrease the coupling ratio from the first waveguide to the second waveguide.

An apparatus comprising:

• a substrate;
• a waveguide integrated with the substrate;
• a layer of optical phase-change material disposed on the waveguide;
• and
• a doped silicon heater, integrated with the substrate, to heat the layer of optical phase-change material, thereby switching the layer of optical phase-change material, at least in part, between an amorphous phase and a crystalline phase.

An optical element comprising:

• a substrate having a surface;
• a first meta-atom formed from a first material on the surface of the substrate, the first meta-atom having a first three-dimensional structure with at least one maximum transverse dimension, in a direction parallel to the surface of the substrate, less than a wavelength of light for which the optical element is designed to operate on;
• first phase change material adjacent to the first material of the first meta-atom;
• and
• a first heating element to heat the first phase change material thereby changing the first phase-change material, at least in part, between an amorphous state with a first refractive index and a crystalline state with a second refractive index different from the first refractive index by at least 0.1.