Chirality-Dependent Orbital Bulk Photovoltaic Effect in a 1D Helical Nanowire.

Bulk photovoltaic effect (BPVE) is a novel nonlinear-optical (NLO) effect for the development of advanced optoelectronic devices. Here, we report a new type of BPVE, chirality-dependent orbital BPVE (orbit-BPVE), in a one-dimensional (1D) helical system, whose orbital-polarized photocurrent is solely determined by the chirality. This orbit-BPVE is contributed by the chirality-dependent orbital angular momentum (OAM), and the chirality-locked spin-BPVE is a secondary effect arising from the orbit-BPVE, mediated by spin-orbit coupling (SOC). The minimal-model calculations further demonstrate that the robust orbit-BPVE persists even at small screw angles and varying SOC strength, and the orbit-BPVE remains more pronounced than spin-BPVE in a wide range of SOC strengths. These results establish 1D chiral systems as a universal platform for orbitronic device engineering, where geometric chirality directly encodes optoelectronic functionality.