Spatial structure of lasing modes in wave-chaotic semiconductor microcavities

Stefan Bittner,Yongquan Zeng,Qi Jie Wang,Hui Cao,Kyungduk Kim

doi:10.1088/1367-2630/ab9e33

Abstract

We present experimental and numerical studies of broad-area semiconductor lasers with chaotic ray dynamics. The emission intensity distributions at the cavity boundaries are measured and compared to ray tracing simulations and numerical calculations of the passive cavity modes. We study two different cavity geometries, a D-cavity and a stadium, both of which feature fully chaotic ray dynamics. While the far-field distributions exhibit fairly homogeneous emission in all directions, the emission intensity distributions at the cavity boundary are highly inhomogeneous, reflecting the non-uniform intensity distributions inside the cavities. The excellent agreement between experiments and simulations demonstrates that the intensity distributions of wave-chaotic semiconductor lasers are primarily determined by the cavity geometry. This is in contrast to conventional Fabry–Perot broad-area lasers for which the intensity distributions are to a large degree determined by the nonlinear interaction of the lasing modes with the semiconductor gain medium.

Highlights

Broad-area semiconductor lasers are commonly employed for high-power applications such as machining, material processing or medical surgery
Our aim is to understand the roles that the cavity geometry and the nonlinear modal interactions play in determining the lasing intensity distributions of wave-chaotic cavities
The excellent agreement of the ray tracing results with the experimental data and passive cavity wave simulations confirms that the ray simulations can predict precisely the intensity distributions inside and outside the D-cavity and stadium microlasers

Summary

Introduction

Broad-area semiconductor lasers are commonly employed for high-power applications such as machining, material processing or medical surgery. The emission intensity distributions are not determined by the passive cavity resonances since the nonlinear interactions of the optical field with the gain medium lead to lensing and self-focusing that create spots of high intensity, so-called filaments [1,2,3]. The lasing emission intensity distributions on the cavity boundary are very inhomogeneous with regions of high as well as very low intensity [13]. This experimental observation raises the question to what extent the structure of the lasing modes is influenced by the asymmetric cavity geometry and the nonlinear light–matter interaction, respectively

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Methods

Conclusion