Mode characteristics of VCSELs with different shape and size oxidation apertures

Abstract

Vertical Cavity Surface Emitting Laser (VCSELs) as the ideal light source for rubidium (Rb) and cesium (Cs) atomic clocks is analyzed for its mode and polarization control. We fabricated three kinds of shapes: triangular, elliptic and circular oxidation aperture which also has different sizes. We formed 3 different shape oxide apertures by wet-oxidation with 36-39μm circular mesa. Our results show that triangular oxidized-VCSELs has the advantages of mode and polarization selection over elliptic and circular oxide aperture. When triangular oxide-confined VCSELs emit in single mode, the measured Side Mode Suppression Ratio (SMSR) is larger than 20 dB and Orthogonal Polarization Suppression Ratio achieves 10 dB. Resonant blueshift of VCSELs with triangular and elliptic aperture is observed with the decrease of aperture size.