Spatially-resolved insulator-metal transition for rewritable optical gratings

Yuliang Chen,Liyan Xie,Chongwen Zou,Jun Jiang,Changlong Hu,Hui Ren,Guobin Zhang,Xiaoyu Zhou,Bowen Li,Liang Li

doi:10.1038/s43246-021-00141-2

Abstract

Optical relief gratings are usually composed of physical grooves with a constant periodicity, and typically suffer from light scattering, are mechanically fragile and are single function. Here, we develop WO3-based gratings by using a recently reported electron-proton synergistic doping route under ambient conditions. This doping strategy is compatible with conventional ultraviolet photolithography, and we show that it induces a selective insulator-metal phase transition and coloration in WO3, with spatial-resolution up to micron-scale. Due to the electrochromic-induced-contrast, a WO3 volume phase grating without grooves and a WO3 relief grating with tunable periodicity are demonstrated. Both gratings can be rewritten after a reset procedure by annealing in air. Our experiments demonstrate WO3–based gratings and an attractive technique for rewritable oxides.

Highlights

Optical relief gratings are usually composed of physical grooves with a constant periodicity, and typically suffer from light scattering, are mechanically fragile and are single function
When an oxide contacted with a proper metal particle are immersed into an acid solution, the electrons supplied by metal and the free protons in acid solution can be doped into oxide together rather than the oxide being corroded by acid
To conclude, we applied electron–proton synergistic doping to WO3 film successfully and realized a direct visualization of insulator–metal transition in WO3 film due to its pronounced electrochromic effect

Summary

Introduction

Optical relief gratings are usually composed of physical grooves with a constant periodicity, and typically suffer from light scattering, are mechanically fragile and are single function. We develop WO3-based gratings by using a recently reported electron-proton synergistic doping route under ambient conditions This doping strategy is compatible with conventional ultraviolet photolithography, and we show that it induces a selective insulator-metal phase transition and coloration in WO3, with spatial-resolution up to micron-scale. The spatially-resolved MIT and coloration in hydrogenated WO3 were feasible up to micrometer scale Based on this unique doping technique, we achieved a planar grating without physical grooves, which can be taken as a kind of new volume phase grating with intrinsically low scattering[18,19]. A WO3 relief grating with tunable period was fabricated by the selective synergistic doping These WO3-based gratings can be reprocessed after a “reset” process by annealing in air, making the devices controllable and reusable. This advanced doping technology opens up alternative approaches for developing optical devices, and rewritable ions devices and integrated circuits for various oxide electronics

Methods

Results

Conclusion