Spontaneous emission factor and its scaling in vertical cavity surface emitting lasers

We report room‐temperature measurements of the spontaneous emission factor β in high‐quality gain‐guided GaAs/AlGaAs vertical cavity surface emitting lasers. In devices with 6‐μm diameter we obtain β=2.8×10−3. The measured scaling of β with the cavity volume agrees well with classical electromagnetic model of dipole radiation. The magnitude of β exceeds that predicted by classical theory by approximately a factor of 2.