Dynamics of capillary condensation in bistable optical superlattices

The optical transmission through a porous superlattice is modulated by capillary condensation and evaporation of ethanol. The system exhibits optical bistability, with the two stable states characterized by a different amount of liquid ethanol in the pores. Switching between states is controlled by the input power of the incident light beam. By tuning the input power at various speeds, we study the dynamics of condensation and evaporation and study the behavior of the hysteresis and switching thresholds. We find that the time response of the system is limited by the condensation process, which is faster in pores with lower radius. We also report on the dependence of the hysteresis loop on vapor concentration.