Shaping the light of VCSELs through cavity geometry design.

Vertical-cavity surface-emitting lasers (VCSELs) are essential in modern optoelectronic systems, driving applications in high-speed optical communications, 3D sensing, and LiDAR. While significant progress has been made in improving VCSEL performance, the role of cavity geometry in optimizing key optical characteristics remains insufficiently explored. This study systematically examines how distinct cavity geometries-circular, square, D-shaped, mushroom-shaped, and pentagonal-affect both the static and dynamic properties of broad-area VCSELs. We analyze their effects on optical power, multimode behavior, beam profile, spatial coherence, and polarization dynamics. Our results show that breaking the continuous rotational symmetry of the cavity effectively increases gain utilization and power, changes the multimode lasing characteristics, shapes the beam, and modifies the polarization. Notably, the pentagonal VCSEL exhibits more than twice the optical power density of its circular counterpart. It also supports the highest number of modes and the fastest mode dynamics, driven by strong mode interaction. These properties make it a strong candidate for high-speed entropy generation. Mushroom-shaped VCSELs demonstrate high power and low spatial coherence, making them ideal for speckle-free imaging and illumination applications. Meanwhile, D-shaped VCSELs provide the most stable polarization and controllable multimode behavior with high power, showcasing their potential for applications that require stable and low-coherence light sources. This study offers a comprehensive analysis of the impact of cavity geometry on VCSEL performance, which provides insights for optimizing VCSEL designs tailored to diverse applications that require distinct properties with broad applicability to advanced imaging, sensing, optical coherence tomography, high-speed communication, and other photonic technologies.