We describe and demonstrate a method of decreasing the divergence angle of multi-mode VCSELs, and show how we can obtain a low and stable divergence angle. We first explain the relationship between the lateral wave-vectors of resonant modes and the divergence angle. Then we attempt to optimize the oxide aperture and the electrode structure. Here, we calculate the electro-magnetic field of the VCSELs by the Finite Difference Time Domain (FDTD) method and the far-field pattern by combining the diffraction integral and the FDTD. Finally, we compare the theoretical and experimental results of the divergence angle of the VCSELs.
We have optimized the doping levels in distributed Bragg reflectors (DBRs) and GaInNAs/GaAs quantum well (QW)
structures in order to enhance their optical output power. We achieved high output power GaInNAs vertical-cavity
surface-emitting lasers (VCSELs) emitting at 1260nm. The continuous wave (CW) output power of the devices reached
3.0mW at room temperature, with a slope efficiency of 0.28W/A. The devices consisted of conventional n-type and ptype
doped DBRs with GaInNAs/GaAs 3QWs, and they were grown by metalorganic chemical vapor deposition