Patent ID: 7221819

Claim:
An optical switch comprising: an optical structure at a first temperature and containing: a set of first waveguide segments; a set of second waveguide segments defining optical paths that cross optical paths of the first waveguide segments; and a set of cavities at intersections of the first waveguide segments and the second waveguide segments; and a liquid having an index of refraction matching an index of refraction of the first and second waveguide segments, wherein the liquid is in communication with the cavities, is at the first temperature adjacent to the optical structure, and has a pressure that is less than a partial vapor pressure of the liquid at the first temperature; and a reservoir in fluid communication with the cavities, wherein the reservoir contains a vapor in contact with the liquid, the reservoir being at a second temperature that is lower than the first temperature, wherein the vapor maintains the pressure of the liquid to be less than the partial vapor pressure of the liquid at the first temperature.