High-purity orbital angular momentum states from a visible metasurface laser
H Sroor, Y-W Huang, B Sephton, D Naidoo, A Vallés, V Ginis, C-W Qiu, A Ambrosio, F Capasso and A Forbes
Orbital angular momentum (OAM) from lasers holds promise for compact, at-source solutions for applications ranging from imaging to communications. However, conjugate symmetry between circular spin and opposite helicity OAM states (±ℓ) from conventional spin–orbit approaches has meant that complete control of light’s angular momentum from lasers has remained elusive. Here, we report a metasurface-enhanced laser that overcomes this limitation. We demonstrate new high-purity OAM states with quantum numbers reaching ℓ = 100 and non-symmetric vector vortex beams that lase simultaneously on independent OAM states as much as Δℓ = 90 apart, an extreme violation of previous symmetric spin–orbit lasing devices. Our laser conveniently outputs in the visible, producing new OAM states of light as well as all previously reported OAM modes from lasers, offering a compact and power-scalable source that harnesses intracavity structured matter for the creation of arbitrary chiral states of structured light.