Fig. 1
From: An InP-based vortex beam emitter with monolithically integrated laser
Integrated orbital angular momentum laser. a Integrated OAM laser with shallow-etched DFB laser and deeply etched vortex emitter on InGaAsP/InP wafer. Inset reveals the cross-section of the vortex emitter. b SEM image of the fabricated OAM emitter. c, d Top and cross-sectional view of the top-grating structure
