Limits of the modulation response of a single-mode proton implanted VCSEL

The limitations of the direct modulation bandwidth for proton implanted vertical-cavity lasers were explored. The measured damping factor of an optimized device, implies a possible bandwidth of up to 80 GHz. However, the intrinsic (parasitic free) carrier transport/capture time of /spl sim/15 ps limits substantially the actual frequency response. The actual measured bandwidth$14.5 GHz was limited also by the emerging of higher lasing modes. The combined effects of shape, size and implantation dose should be optimized to reach the limit of the direct modulation of these lasers.