Purcell effect and the bias-free pulse response of vertical-cavity surface-emitting lasers

Although microcavity confinement has been proposed for some time as a means to improve laser characteristics, it has been difficult to connect these predictions to actual laser characteristics. We believe that the reason for this is at least partly due to the lack of rate equations that accurately include the microcavity confinement in terms of straightforward design parameters such as the mode size or spontaneous linewidth. Instead, great emphasis is placed on the spontaneous coupling coefficient β without considering how β explicitly depends on the cavity and active region parameters. This has prevented the inclusion of the cavity effects in rate equations In general, β depends on the mode volume, the optical loss rate, the spontaneous linewidth, and the spontaneous lifetime, and the expression for β is known explicitly only in the limit that the cavity loss rate greatly exceeds the emitter dephasing rate (or spontaneous linewidth). We present experimental results showing the change in the spontaneous lifetime that can be achieved in apertured-microcavities such as the oxide-confined vertical cavity surface-emitting lasers. A cavity with InGaAlAs quantum dot (QD) light emitters is used to obtain electronic confinement to the aperture