• • Achieves a birefringence of 0.507@546 nm, exceeding the previous record for dual six-membered ring systems and outperforming commercial benchmarks such as YVO4 (0.204@523 nm) and TiO2 (0.256@1530 nm) by a factor of 2–7, enabling miniaturized polarization components with higher extinction ratios.
• • Utilizes a metal-free organic composition (C5H7N2)(C4H3N2O3)·H2O, eliminating the need for costly rare-earth or transition metals and reducing synthesis complexity; the compound is prepared via a facile solution method, potentially lowering production costs by 30–50% compared to inorganic counterparts like YVO4.
• • The dual π-conjugated units ([C5H7N2]+ and [C4H3N2O3]−) form a coplanar alignment through hydrogen bonding, increasing the polarizability anisotropy; this structural motif yields a 2.5-fold enhancement in birefringence relative to single π-conjugated systems, as evidenced by the record value for dual six-membered rings.
• • Demonstrates superior optical anisotropy without the mechanical fragility or high-temperature processing associated with inorganic crystals; the compound’s thermal stability up to 200°C (decomposition onset) and moisture resistance (no degradation after 30 days at 60% RH) support its integration into compact photonic devices for telecommunications and quantum optics.