Reduced threshold all-optical bistability in etched quantum well microresonators

All-optical bistability is demonstrated in GaAs/AlGaAs multiple quantum well microresonators fabricated by SiCl4 reactive ion etching. A fabrication process has been developed in order to obtain low threshold bistability. The studied samples are two-dimensional 15×15 arrays of cylindrical microresonators of 4 μm diam and 6 μm height. Owing to lateral carrier and light confinement, bistability is observed with a strongly reduced threshold power, below 100 μW. This result was obtained without post-etching surface treatment. The low bistability threshold suggests that the surface recombination rate is reasonably small, possibly due to some self-passivation occurring during the etching process.