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

Area of Science:

• Optoelectronics
• Metamaterials
• Laser Technology

Background:

• Edge-emitting lasers (EELs) offer high power and efficiency but suffer from divergent, asymmetric far-field beams due to anisotropic quantum wells.
• Controlling beam propagation angles and polarization states of EELs is crucial for many applications.

Purpose of the Study:

• To propose and demonstrate an integrated beam shaping/collimating and polarization manipulating metasurface (BS/C-PMM) for EELs.
• To address the inherent astigmatism and polarization issues of EELs.

Main Methods:

• Designed an asymmetric phase profile for beam shaping, utilizing GaN nanopillars of varying shapes and sizes to correct for EEL astigmatism.
• Incorporated Pancharatnam-Berry phase via nanopillar azimuthal orientation for polarization manipulation.
• Fabricated a 1mm x 1mm BS/C-PMM and integrated it with a 980nm EEL.

Main Results:

• Reduced laser beam divergence angles from 35.54°/15.75° to 0.707°/0.649°.
• Decreased the beam spot aspect ratio from 3.05 to 1.03, achieving near-circularity.
• Converted linear polarization to left-circular polarization with 43.1° ellipticity, closely matching theoretical predictions.

Conclusions:

• The integrated BS/C-PMM effectively corrects EEL astigmatism, collimates the beam, and precisely controls polarization.
• Demonstrated practical feasibility for advanced integrated optoelectronic devices requiring tailored beam characteristics and polarization states.