Control of lasing in fully chaotic open microcavities by tailoring the shape factor

The authors demonstrate experimentally that lasing in a semiconductor microstadium can be optimized by controlling its shape. Under spatially uniform optical pumping, the first lasing mode in a GaAs microstadium with large major-to-minor-axis ratio usually corresponds to a high-quality scar mode consisting of several unstable periodic orbits. Interference of waves propagating along the constituent orbits may minimize light leakage at particular major-to-minor-axis ratio. By making stadium of the optimum shape, the authors are able to maximize the mode quality factor and align the mode frequency to the peak of the gain spectrum, thus minimizing the lasing threshold.