Impact of Oxide Aperture Geometry on Noise Performance Degradation in 850 nm Multimode VCSELs for Datacom Applications

We study an 850 nm multimode VCSEL with an elliptical oxide aperture. The device is dynamically modeled through a time domain mode expansion approach, accounting for coherent mode coupling and spatial hole burning. Here, Relative Intensity Noise (RIN) spectra display spurious peaks, limiting the device performance. Analytical considerations and electromagnetic simulations allow us to identify good parametric regions for aperture geometry design, potentially improving the laser noise performance.