A thermal conductivity and phase transition heat transfer mechanism incorporates an active optical element. Examples of active optical elements include various phosphor materials for emitting light, various electrically driven light emitters and various devices that generate electrical current or an electrical signal in response to light. The thermal conductivity and phase transition between evaporation and condensation, of the thermal conductivity and phase transition heat transfer mechanism, cools the active optical element during operation. At least a portion of the active optical element is exposed to a working fluid within a vapor tight chamber of the heat transfer mechanism. The heat transfer mechanism includes a member that is at least partially optically transmissive to allow passage of light to or from the active optical element and to seal the chamber of the heat transfer mechanism with respect to vapor contained within the chamber.