Aligned Fiber Induced Laser-Driven Bamboo Diffuser Enabling Highly Directional Illumination Applications

Abstract

Directional optical diffusers provide customizable spatial intensity light distributions and have potential applications in next-generation directional lighting devices. The manufacturing procedures for directional lighting devices suffer from insufficient directionality, complex manufacturing conditions, and unsustainability. Herein, bamboo is processed directly into a directional laser-driven bamboo diffuser (LDBD) by delignification and subsequent impregnation with a polymer (poly(ethylene glycol)diacrylate and epoxy acrylate) with a mismatched refractive index. The LDBD shows a distinctly elliptical directional light distribution under laser irradiation. Then, a bright, efficient, and tunable white directional lighting from Y₃Al₅O₁₂:Ce³⁺ (YAG: Ce)-added LDBDs is obtained by regulating the power of a 450 nm laser and YAG: Ce concentration. Optimal white lighting by the LDBD is obtained at a power of 400 mW and 1% YAG: Ce concentration. This provides standard white CIE 1931 chromaticity coordinates (0.33, 0.33), suitable correlated color temperature (5406 K), and high color rendering index (81.2%). Furthermore, the optimized bamboo diffuser exhibits satisfactory mechanical properties, as well as long-term thermal and water resistance. Due to the unique materials design and facile fabrication strategy, LDBD shows promise for optical fiber-guided, non-contact, long-distance, undersea, and other highly directional laser lighting applications.