Extreme Geometry-Induced Optical Chirality in Vertically Nanoprinted Hollow-core Light Cages

Chiral photonic waveguides are essential for generating, manipulating, and transporting complex light states, yet their integration remains constrained by geometric and fabrication limitations. Here, we introduce vertically nanoprinted twisted light cages (tLCs) as a new class of chiral on-chip hollow-core waveguides that support strong chiral mode formation and enable extraordinary high geometry-induced optical activity. This approach overcomes long-standing challenges in twist rate, mechanical stability, and mode control faced by fiber- and chip-based systems. We report record-high circular birefringence and circular dichroism, achieved in combination with exceptionally high twist rates. In addition to strong chiral light–matter interaction, tLCs provide a compact platform for complex light generation, alternative to metasurfaces and resonant structures. Their lateral core access and potential for on-chip integration enable sophisticated polarization control and structured light applications in quantum optics and biosensing, bridging the gap between chiral photonics and integrated systems for next-generation on-chip chiral photonics.