Solid Deep Ultraviolet Diffracting Inverse Opal Photonic Crystals

摘要： We fabricated the first solid, mechanically robust inverse opal photonic crystals that diffract in the deep ultraviolet (UV) spectral region. These photonic crystals are fabricated by self-assembling <140 nm diameter monodisperse polystyrene nanoparticles into face centered cubic 3D close-packed structures on fused silica microscope slides in the presence of tetraethyl orthosilicate via a vertical deposition method. Tetraethyl orthosilicate condenses in the nanoparticle interstices during self-assembly, immobilizing the polystyrene nanoparticles in a SiO2 matrix. Removal of the polystyrene nanoparticles using Piranha solution yields a stable SiO2 inverse opal structure that Bragg diffracts in the deep UV at <245 nm. We measured the UV-Vis transmission, diffraction of a collimated deep UV white light source, and diffraction of 229 nm laser light in order to characterize the deep UV optical performance of these photonic crystals. We measured a maximum light attenuation of ~98% at the Bragg condition, calculated a photonic crystal thickness of ~33 layers, and calculated a diffraction spectral bandwidth of 16.8 nm full-width at half maximum. The mechanical robustness, photochemical durability, and shelf-life of the deep UV diffracting photonic crystals demonstrated in this work enables their development for use as deep UV optical devices. We conclude that additional optimization of the self-assembly and vertical deposition conditions is required to improve the thickness uniformity and ordering of these photonic crystals to increase their diffraction efficiency and to decrease their diffraction bandwidth.