Charge-induced self-feedback optical bistable device: switching time and spatial resolution

Abstract

We report extensive experimental and theoretical studies on the properties of an optical bistable device called the charge-induced self-feedback device (CSFD) which is a variation of a self electro-optic effect device (SEED). In the mechanism, a novelty: of the CSFD consists of the feedback due to field-screening, resulting in independent switchings of optical beams focused at different spots on the CSFD without the help of pixellated structures. We experimentally demonstrate independent switchings without pixellation. In addition, a spatial resolution of the CSFD on such a device operation is found to be limited by an in-plane spreading of photoexcited carriers enhanced by a lateral electric-field induced by photoexcitation. Also, it is experimentally demonstrated that shortening carrier escape times leads to an improvement on the spatial resolution in terms of the suppression of the in-plane carrier spreading. Furthermore, an investigation on dynamics of the photoexcited carriers in the device reveals that the switching time of the CSPD is on the order of nanosecond, limited mainly by the hole escape time. >