Fig. 4
From: An InP-based vortex beam emitter with monolithically integrated laser

OAM mode characterization. a OAM lasing modulated by SLM. The first row shows holograms of the SLM. The second and third rows are patterns of the RHCP and LHCP components after being reflected by the SLM in the first row, indicating l = + 4. b Mode purities of the OAM lasing measured by the SLM. c Mode purities of the RHCP and d LHCP components of the OAM-carrying beams radiated by the OAM emitter