Spontaneous emission alteration in InGaAs/GaAs vertical cavity surface emitting laser (VCSEL) structures

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Abstract
The spontaneous emission from vertical-cavity surface-emitting laser (VCSEL) structures consisting of an In0.2Ga0.8As/GaAs quantum well and AlAs/GaAs distributed Bragg reflectors (DBRs) was systematically investigated as a function of reflectivity of DBRs, energy difference between the excitonic energy and the cavity mode and emission wavelength. Significant lifetime alteration, which was much more than that of the previous experimental results and the theoretical estimation based on the atomic dipole model, was observed when the reflectivity was changed. This was attributed to the cooperation between the microcavity effect and the carrier-carrier scattering effect which is not considered in the atomic dipole model. The spontaneous emission lifetime of the VCSEL structure whose gain peak is not equal to the cavity mode was found to be changed depending on the energy difference between the excitonic energy and the cavity mode and the lifetime was the shortest when the excitonic energy was equal to the cavity mode. It was also observed that the spontaneous emission lifetime depends on the emission wavelength and was the shortest at the cavity mode, the reason for which has not been fully clarified yet.