High-performance SiOx planarized GaInNAs VCSELs

In this article, we report on an alternative method to fabricate high-efficiency planar-type oxide-confined 1.3-μm vertical-cavity surface-emitting lasers (VCSELs). The planarized process of VCSELs uses silicon oxide (SiO_x) as a buried layer. The devices exhibit excellent static characteristics at room temperature, including a threshold voltage of 2 V corresponding to a threshold current of 3.5 mA, and a maximum light output power of 1.86 mW measured at 15 mA. To our knowledge, this output power is the best when compared to those obtained with conventional VCSEL processes for the similar epitaxial structure design (reference of the OLD values). The VCSELs show a threshold current density of 3100 A/cm², a differential resistance at half of the maximum power of 110 Ω, a slope efficiency of 0.22 W/A above the threshold, and a continuous wave operation temperature of up to 80°C. In addition, when operating at 4 mA these devices exhibit a single-mode emission with the transverse-mode suppression of more than 20 dB and an output power of 0.12 mW. The wavelength of the strongest emission peak, which corresponds to the fundamental transverse mode, increases with injection current at a red shift of 0.45 nm/mA from 1280.6 nm at 4 mA to 1284.4 nm at 12 mA due to a joule effect. Finally, this planar-type 1.3-μm VCSEL shows a clear and symmetric eye diagram operating at 2.488 Gb/s at 12 mA. These results confirm the SiO_x-planarized GaInNAs VCSELs have the potential capacity for fiber optic applications.