ETCHED ARRAYS OF QUANTUM-WELL OPTICAL BISTABLE MICRORESONATORS

We report the operation of etched GaAs/AlGaAs multiple quantum well mi croresonators as low threshold all-optical bistable devices. The studi ed samples are 2-dimensional arrays of cylindrical microresonators of 6 mum height, with diameters of 4 mum and 6.4 mum. They are realized b y SiCl4 reactive ion etching of an epitaxial high finesse vertical mic rocavity structure. Due to the lateral carrier and light confinement, optical bistability is observed with a strongly reduced threshold powe r, below 100 muW for the 4 mum diameter devices. The optical confineme nt allows to achieve a high cavity Q factor in a reduced volume, and l eads to the observation of multiple hysteresis loops due to the transv erse mode structure of 6.4 mum diameter microresonators. The low bista bility threshold, obtained without post-etching surface treatment, is attributed to a self-passivation occurring during the etching process, as evidenced by the observation of a thin coating film protecting the microresonator vertical surfaces.