3D Engineering of Orbital Angular Momentum Beams via Liquid‐Crystal Geometric Phase.

Orbital angular momentum (OAM) provides a novel degree of freedom for light, deeply inspiring versatile light‐matter interactions and large‐density multiplexing computing. Recently, multimode and multichannel control of OAM beams have aroused extensive curiosity, whereas their flexible engineering in 3D space still remains challenging. Here, a new type of liquid‐crystal geometric phase optical elements is demonstrated to achieve on‐demand 3D tailoring of OAM beams. Via integrating binary and continuous phase patterns into photo‐aligned liquid crystals, customized 3D lattices of identical or propagation‐variant OAM beams are generated in an electrically tunable broadband manner. By altering the incident spin, these volumetric OAM beams can be switched among different states on the higher‐order Poincaré sphere. This work demonstrates a practical approach toward efficient OAM harnessing with large channel capacity and high spatial mode diversity, holding great potential for 3D optical manipulation, recording, and microscopy. [ABSTRACT FROM AUTHOR]