Integrated beam shaping/collimating and customized polarizing edge-emitting lasers with single GaN metasurface

Edge-emitting lasers (EELs) have been widely applied in many fields due to the advantages of high power, high efficiency and compactness. However, the propagation angles along the fast and slow axis and the polarization state of the laser in the far field are highly divergent, asymmetric and fixed due to the anisotropic structure of the quantum well. Here, we propose and experimentally demonstrate a beam shaping/collimating and polarization manipulating metasurface (BS/C-PMM) integrated EEL. The phase for the beam shaping/collimating is asymmetrically designed with double foci corresponding to the fast and slow axis, and achieved by a GaN nanopillar array with different shapes and sizes to match intrinsic astigmatism along two orthogonal axes of the quantum well of the EEL. Furthermore, the azimuth angle corresponding to Pancharatnam-Berry phase is added onto each nanopillar to manipulate the polarization state of the laser beam, resulting in an integrated EEL chip. The proposed BS/C-PMM is fabricated with a size of 1 mm × 1 mm and integrated with an EEL with a wavelength of 980 nm. Experiment results show that the divergent angles of the laser beam can be significantly reduced from 35.54° and 15.75° to 0.707° and 0.649°, and the ratio of the long axis to the short axis of the beam spot decreases from 3.05 to 1.03, respectively. Simultaneously, the linearly polarized beam initially from the EEL is converted to a designed left-circular polarization state with an ellipticity of 43.1°compared to the theoretical prediction of 45°. The proposed BS/C-PMM demonstrates a practical feasibility for integrated EELs with combined beam shaping/collimating and polarization manipulation.