Sc2O3 on sapphire all-crystalline grating-waveguide resonant reflectors

This paper reports the fabrication and first demonstration of all-dielectric crystalline grating-waveguide reflectors comprising a Sc2O3 waveguide grown on a sub-wavelength-patterned sapphire substrate. Rigorous coupled-wave analysis is employed to simulate the operation of the structure, suggesting a 100% resonance reflectivity in theory. Structuring of the sapphire substrate is achieved using inductively coupled plasma etching, whilst pulsed laser deposition is used for epitaxial growth of the Sc2O3 crystalline waveguide. Devices with distinct TE- and TM-polarisation resonances around 1030-nm for an angle of incidence near 10 degrees are demonstrated, with reflectance approaching 90%. The discrepancy in reflectivity is attributed to the waveguide thickness variation and surface roughness. Refinement of the fabrication processes and tolerances should lead to improvement in the surface quality of the crystalline grating-waveguide structure and operation closer to the ideal resonance reflectivity.

Automated summary

This paper presents the fabrication and first demonstration of all-dielectric crystalline grating-waveguide reflectors consisting of a Sc2O3 waveguide grown on a sub-wavelength-patterned sapphire substrate. Rigorous coupled-wave analysis is used to simulate the structure, showing a theoretically 100% resonance reflectivity. The sapphire substrate is patterned using inductively coupled plasma etching, while the Sc2O3 crystalline waveguide is grown through pulsed laser deposition. Devices with distinct TE- and TM-polarisation resonances are demonstrated, with reflectance close to 90% at an angle of incidence near 10 degrees. Refining the fabrication processes and tolerances should improve the surface quality and achieve resonance reflectivity closer to the ideal state.