A Transparent, High Refractive Index and Abbe Number Polymer for Visible Metalens by High Fidelity Nanoimprinting

ABSTRACT Simultaneously achieving high visible transparency, high refractive index ( n ), and a large Abbe number ( υ D ) in organic polymers remains a fundamental challenge. Here, a facile and efficient dual sulfur‐mediated Michael addition strategy is reported to synthesize transparent high refractive index polymers (HRIPs) with large υ D . By combining main backbone de‐conjugation to preserve visible transparency with rational side‐chain engineering for n ‐tuning, the optimal polymer (H4) achieves an ultrahigh n of 1.86 at 589 nm alongside a large υ D of 34.93 and robust stability. Moreover, polymer H4 exhibits remarkable performance in nanoimprint lithography, replicating features down to 75 nm with aspect ratios up to 8.5 and a low volumetric shrinkage of only 3.23%. Notably, a nanoimprinted metalens prototype fabricated from H4 delivers a relative focusing efficiency of 49.8% at 550 nm (NA = 0.5), approaching the theoretical design value (52.94%). Therefore, the high refractive index polymer H4 bridges molecular design and manufacturable meta‐optics, showing tremendous potential in scalable, flexible, next‐generation photonic platforms by translating side‐chain polarizability engineering into practical wavefront control.