Red VCSELs for emission wavelengths near 650nm find applications in emerging technologies such as plastic-fiber-based data communication. However, these devices are challenging due to low band offsets and high electrical and thermal resistivity of especially the p-DBR. The paper presents the optimization of p-DBR and QW design for the reduction of the series resistance and the threshold current density. VCSEL structures were grown using MOVPE and processed to air-post mesas. The resistance of the p:DBR mirrors was optimized using different dopants and interfaces. By changing from Zn doping and abrupt interfaces to the dopant C and introducing graded interfaces the differential resistance decreased. Due to a relative shift across the wafer between the DBR stop-band and gain peak wavelength defined by the MQW active region, devices are available with lasing wavelengths between 638nm and 662nm in pulsed-mode operation. Threshold current densities of 3.6kA/cm2 at 650nm are measured. For improving device parameters a current aperture was processed by selective wet oxidation of AlxGa1-xAs with varying x. Cw laser operation is achieved for wavelengths between 644nm and 657nm at 10°C ambient temperature. With threshold currents under 4mA maximum cw output powers of 160µW are obtained at wavelengths of 657nm and 650 nm.

Date Published: 4 May 2001
PDF: 8 pages
Proc. SPIE 4286, Vertical-Cavity Surface-Emitting Lasers V, (4 May 2001); doi: 10.1117/12.424801

Published in SPIE Proceedings Vol. 4286:
Vertical-Cavity Surface-Emitting Lasers V
Kent D. Choquette; Chun Lei, Editor(s)