Bidirectional Refractive-Index Programming via Three-Stage Sequential Thiol-Click Chemistry for High-Performance Holographic Recording
Year: 2026
Type: preprint
Abstract: Conventional holographic photopolymers (HPs) mainly rely on a polymerization–diffusion mechanism to record volume holographic gratings (VHGs), resulting in trade-offs among photosensitivity, refractive-index (RI) modulation (Δn), optical clarity, and VHG stability. To address these trade-offs, we propose a bidirectional refractive-index programming (BRIP) strategy based on three sequential thiol-click reactions. Stage I employs a base-catalyzed thiol–acrylate Michael addition to form a thiol-rich host matrix. Under holographic exposure, Stage II triggers photoinduced thiol–vinyl addition to incorporate a high-RI recording monomer into the bright regions, generating the initial VHG Δn while preserving residual thiol sites in the dark regions. After exposure, Stage III uses thermally activated thiol–epoxy addition to incorporate a low-RI enhancing monomer into these complementary dark regions, further increasing Δn. A representative BRIP HP formulation is developed to validate the strategy. Benefiting from the BRIP design, the material requires only 1.1–1.9 mJ/cm2 exposure dose to generate VHGs with initial Δn values of 0.0103–0.0232 after Stage II, which increase to 0.0193–0.0394 after Stage III, while maintaining >95% visible-light transmittance, <0.02% haze, and <4% Δn variation after ten thermal cycles between 200 and -197 °C. This work establishes a new molecular design paradigm for high-performance HPs.
Source: ChemRxiv
Authors: Haoqiang Gao, Mingxuan Wang, Diqin Zhang, Yunlong Zhang, Qixin Zhou, Yong Bi, Yuxia Zhao
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G2475927552, G6181471720
OpenAlex ID: W7214155627