Guided-mode-resonance phase mask for compact laser-interference lithography

We propose a concept for compact laser-interference lithography with integral suppression of the parasitic zero-order beam. The device combines a first-order diffraction grating with a subwavelength guided-mode resonance reflector implemented in a fully dielectric TiO₂/SiO₂ platform. The upper grating efficiently generates the ±1 diffraction orders, while the lower resonant layer selectively reflects the transmitted zero-order component through resonance excitation. Rigorous coupled-wave analysis shows that the combined structure transfers approximately 90% of the incident ultraviolet laser power into the two first diffraction orders while suppressing the zero-order transmission below 0.1% near the i-line wavelength of 365 nm. The resulting interference pattern exhibits extremely high contrast with calculated fringe visibility exceeding 0.999 and a period of 215 nm in the example design presented. The proposed architecture eliminates the need for external beam-management optics and provides a compact, alignment-stable, and scalable approach for high-quality interference lithography applicable to Bragg gratings, metasurfaces, resonance lattices, and other periodic nanophotonic structures.