Miniature wide-spectrum mode sorter for vortex beams produced by 3D laser printing

Optical vortex beams can be used as carriers of information in optical communication and quantum optics applications. Owing to their spatial orthogonality, these beams can be multiplexed and demultiplexed, but up until now this was primarily achieved by bulky and large devices. In this work, a new approach is used to fabricate miniature vortex mode sorters based on three-dimensional laser printing, thereby enabling direct integration into optical systems. Mode sorters that are composed of two separate elements as well as a single integrated device are presented. These devices can handle both pure andmixed vortex beams with topological charge |l| ≤ 3 and |l| ≤ 2 for the dual-element device and integrated system, respectively. Mode-sorter spectral bandwidth and surface-quality effects are also discussed.