Fabrication and characterization of a planarized vertical-cavity surface-emitting laser by using the silicon oxide

Abstract

In this article, an alternative method is presented to fabricate a planar-type oxide-confined 850-nm vertical-cavity surface-emitting laser (VCSEL). The threshold voltage, threshold current, light output power, external differential quantum efficiency, emission spectrum, and dynamic response of VCSELs planarized with a silicon oxide (SiOx) have been evaluated. These devices exhibit excellent static characteristics, including a threshold voltage (Vth) of 2.05V corresponding to a threshold current of 0.88mA, a minimum threshold current of 0.7mA near 60°C, a maximum output power of 4.28mW at 11mA, a maximum external differential quantum efficiency (ηex) of 43% just above threshold, and an operation temperature beyond 130°C. In addition, the transverse modes of the device initially are low-order, while high-order modes appear at elevated current levels. The fundamental transverse mode at the longest wavelength increases with injected current with a redshift of 0.49nm∕mA due to the Joule effect. Since the thermal resistance of the VCSEL with a SiOx buried layer is less than that of device without it, the VCSEL with the buried layer displays less redshift and better performance. Finally, the VCSEL with a SiOx buried layer shows a clear eye-opening feature as operating at 2.488Gbit∕s with a bias current of 2mA. Further increasing the current level, the device can work at the maximum bit rate of 8Gbit∕s and a bias current of 3.7mA.