Nanolasers Heat Up - Technology Review: The team's device contains a 45-nanometer-thick, 1-micrometer square of cadmium sulfide, a semiconductor used in some solar cells and photoresistors for microchip manufacturing. The square rests on a a 5-nanometer slice of magnesium fluoride, atop a sheet of silver. When light from a commercial laser hits the metal, plasmons are generated on its surface. But the cadmium sulfide square confines the plasmons to the gap, reflecting them back each time they hit an edge. Less than 5 percent of the radiation escapes the structure, allowing sustained surface-plasmon lasing, or "spasing," at room temperature. The research was published online in Nature Materials on December 19.
This isn't the first spaser to work at room temperature. In fact, the very first spaser used dye-based materials that work at room temperature. But these materials can only be activated with pulses of light—called optical pumping—which limits applications.