Turn-on Time Delay of Vertical Cavity Surface Emitting Lasers of Different Active Region Diameters

In this paper, we investigated the turn-on time delay (t(on)) of vertical cavity surface emitting laser as a function of active region diameter (D). The analysis is performed according to the influence of D on the threshold carrier density (N-th) and cavity volume. At small D, t(on) takes a very high value due to high value of N-th. The latter increases as D decreases due to increasing of diffraction loss which dominates at small D. While as D increases, the cavity volume increases which leads to deplete the carrier density inside the active region and therefore increase t(on). We show that there is an optimum value of D that gives a minimum t(on) and threshold current.