A switching element includes a bubble chamber, a heater and a heat
conductor. The bubble chamber holds fluid. The bubble chamber includes a
trench within a planar light circuit and includes a trench within an
integrated circuit attached to the planar light circuit. The heater is
located under the trench within the integrated circuit. The heat
conductor is attached to the integrated circuit. The heat conductor is
located within the trench within the integrated circuit. A portion of the
heat conductor is in close proximity to the heater. The heat conductor is
more heat conductive than the fluid within the bubble chamber.