Scaling effects on vertical-cavity surface-emitting lasers static and dynamic behavior

摘要

We investigate the influence of oxide aperture size and number of top distributed Bragg reflector pairs on the performance of oxide confined vertical-cavity surface emitting lasers. Several counteracting mechanisms are shown to result in nonmonotonic behavior, which limits the performance of very small cavities. Static, dynamic, and noise behavior are considered. We examine static operation by means of steady-state measurements, whereas dynamic behavior and noise performance are described by the intrinsic relaxation oscillation frequency, damping coefficient, and Schawlow-Townes linewidth. These parameters are extracted from relative intensity noise measurements. Reducing the oxide aperture up to a given optimal diameter is shown to improve the device's characteristics. We attribute the performance degradation below this value to increased diffraction losses, reduced confinement factor, and enhanced spontaneous emission. Similarly, increasing the number of Bragg reflector pairs first yields better overall performance as a consequence of reduced mirror losses. However, beyond an optimal value, significant reduction of the differential gain is observed that is attributed to gain compression and possibly thermal effects, degrading both the steady-state and high-frequency performance of the device.