Description
The generation of optical vortex beams with varying orbital angular momentum (OAM) beam is crucial across diverse fields, including optical communication, topological photonics, and quantum optics, among others. Recently, photonic crystals (PhCs) have emerged as a powerful platform for generating vortex beams in momentum space, offering significant advantages such as the absence of a geometric center for alignment. However, modifications to the unit cell of a PhC slab can substantially alter its overall momentum-space properties, making it particularly challenging to realize the desired vortex beams and their multiplexing. Here, we present an inverse design framework for PhCs that enables precise generation of vortex beams with tailored properties. We demonstrate the generation of vortex beams with specific OAM orders through PhCs and further achieve polarizationdivision and momentum-space-division multiplexing. This study highlights the potential of PhCs for generating vortex beams with diverse orders and multiplexing schemes. In addition, it expands their functionality in practical applications and offers a new platform to explore their rich topological phenomena.
