Fourier Space Analysis of an Elliptical Micropillar Cavity

We analyze two linearly polarized modes in an elliptical micropillar cavity through Fourier space analysis, where the in-plane wavevector corresponds to the incidence angle with the distributed Bragg reflector (DBR). The Fourier space field pattern shows that the spreading angle along the short axis is larger, so that it has the greatest effect on the reflectivity. The higher quality factor (Q) in the x-polarized mode parallel to the long axis of the elliptical cross-section can be explained by the fact that s-polarization has higher reflectivity for broader incidence angle to the DBR than p-polarization. The calculated Q factors increases with the diameter of the cavity due to smaller spreading angles. This Fourier analysis of the micropillar cavity modes could be widely applied to optimize the cavities for high Q and small V .