Spin‐Selective Chiral Emission and Incoherent Focusing via On‐Chip Meta‐Optics

ABSTRACT Efficient on‐chip generation and control of chiral incoherent light emission are essential for emerging applications in integrated nanophotonics. Although previous on‐chip light‐emitting metasurfaces have achieved various forms of guided photoluminescence (PL) manipulation, high circular dichroism (CD) emission and chiral phase manipulation remain largely unexplored owing to the absence of robust design paradigms for on‐chip excitation and coupling mechanisms. Here, we propose and experimentally demonstrate an on‐chip chiral emission metasurface (OCEM) platform that enables high‐CD unidirectional PL emission and chiral focusing. By breaking the in‐plane mirror and two‐fold rotational symmetries of on‐chip meta‐atoms, we achieve circular‐polarization‐selective emission of guided PL, experimentally yielding a high CD of ∼0.86 in unidirectional PL emission, with a narrow divergence angle of less than 4° and a large diffraction angle of ∼30°. Furthermore, by incorporating a detour‐phase mechanism via spatial displacement of meta‐atoms, chiral focusing of incoherent guided PL is experimentally demonstrated. By unifying spatial coherence engineering, spin‐selectivity, and chiral wavefront control within a single architecture, the OCEM platform substantially expands the functional repertoire of integrated light sources. We envision that this platform will advance integrated chiral photonic devices, offering a versatile and scalable route toward compact circularly polarized light sources and on‐chip chiroptical sensing.