LATCHING BUBBLE FOR FLUID-BASED OPTICAL SWITCH

An optical switch having liquid or bubbles in switching sites operates with a fluid pressure less than the vapor pressure of the liquid. This pressure differential is equal to the surface tension induced pressure drop across a bubble having a critical size selected according to switching site geometry. Each switching site has a stable state including a bubble larger than the critical size and another stable state with no bubble. Local heating provides nucleation energy to create a bubble but is not required to maintain the bubble. Globally or locally increasing the fluid pressure collapses bubbles in switching sites to reset all or selected switching sites. One switching site creates rapidly expanding bubbles near but outside the optical cavity of the switching site. The bubble's expansion causes liquid flow that locally increases pressure and collapses a bubble in the optical cavity or pushes the bubble from the optical cavity into an absorber cavity.