Waveguide Grating Color Reflector Using Germanium Telluride

This paper demonstrates a tunable color filter in an optical waveguide grating architecture consisting of a phase change material, Germanium Telluride (GeTe). The waveguide and grating resonances were used to enhance the color dynamic when GeTe is transitioned between its amorphous and crystalline states. The optical refractive index of the GeTe grating changes in response to an applied heat, which results in different reflected colors. Red, yellow, and green colors were achieved at room temperature for different grating periods in the amorphous phase. When GeTe is transitioned to the crystalline state, these colors change to orange, green, and blue, respectively.