Lead-halide perovskites were demonstrated to exhibit some of the largest known optical nonlinearities, yet their potential for frequency conversion remains largely untapped. Here we demonstrate ultra-broadband four-wave mixing of near- and mid-infrared femtosecond pulses in thick single-crystal LHPs, generating bright, coherent, and highly collimated emission across an exceptionally wide continuous tuning range without phase-matching engineering, angular alignment, or dispersion optimization. Time resolved measurements reveal that the emission originates near the crystal surfaces, where phase-matching constraints are relaxed, while the unusually large intrinsic χ(3) response preserves efficient and directional frequency conversion despite the strongly localized interaction volume. These results position LHPs as a powerful bulk platform for ultra-broadband nonlinear photonics, opening a pathway toward compact, alignment-free architectures for ultrafast frequency conversion.
@article{arxiv.2605.25718,
title = {Alignment-free ultra-broadband parametric frequency conversion in lead-halide perovskites},
author = {Abhishek Shiva Kumar and Dusan Lorenc and Ayan A. Zhumekenov and Osman M. Bakr and Zhanybek Alpichshev},
journal= {arXiv preprint arXiv:2605.25718},
year = {2026}
}