Diode pumped 850 nm vertical-cavity surface-emitting laser

Very little, if any, has been published on optically pumped 850 nm vertical-cavity surface-emitting lasers (VCSELs), particularly for doped structures. This paper investigates GaAs-based VCSELs which have not been optimized for optical pumping work. Characterisation was carried out for both pulsed and continuous wave (CW). Pulsed operation causes a lower rise in temperature, thus postponing the onset of thermal rollover, and allowing the device to be operated at higher powers. A threshold of ∼160 kW/cm², and single mode output with incident power density of up to 225 kW/cm² were obtained. From the simulation work done, it has been observed that for optically pumped VCSELs, at higher pump density, there was faster turn on and higher output power, and that dilute nitride active material give better output performance compared to GaAs.