Effects of Near-Field Phase and Amplitude Deviations on the Far-Field Beam Quality of Hexagonally Packed VCSEL Arrays

Abstract

Vertical Cavity Surface Emitting Laser (VCSEL) coupled arrays are promising for high-power and high-beam-quality applications. However, optical field coupling among array elements in practical operation induces phase and amplitude non-uniformities that degrade far-field beam quality. In this work, the effects of near-field phase and amplitude non-uniformities on the far-field beam quality of hexagonally packed VCSEL arrays are investigated. Based on Gaussian beam propagation theory, a theoretical expression for the far-field intensity distribution is derived, and a 61-element VCSEL arrays is modeled using VirtualLab Fusion to analyze the impact of phase and amplitude deviations on main-lobe coupling efficiency and divergence angle. Simulation results show that increasing phase deviation from 0% to 70% reduces coupling efficiency by 83.9% and increases the divergence angle by 59.5%, whereas amplitude deviations up to 100% cause only minor degradation, indicating that phase non-uniformity dominates far-field beam quality degradation. This provides theoretical support and practical guidance for achieving high-performance, high-beam-quality hexagonally packed VCSEL arrays.