Electrochemical pumping of dye produces stimulated emission
Researchers at Nippon Telegraph and Telephone Company Basic Research Laboratories (Atsugi, Japan) have reported using electrochemiluminescence (ECL)--light produced from electron transfer between electrochemically generated anion and cation radicals--to pump dye molecules at a rate sufficient to produce lasing action. A dye laser that could convert electricity directly into laser output without a pump laser would be smaller and potentially less expensive than current dye-laser systems and might offer more power, tunability, and range of available wavelengths. Previous work in this area has not achieved the ECL efficiency required to reach the optical pumping threshold of the dye.
In this experiment, a pair of sputter-deposited platinum-film electrodes faced each other at a distance of between 2 and 7 µm. A solution of diphenylanthracene (DPA) flowed through the cavity, and a potential was applied to the electrodes. The DPA molecules were oxidized and reduced, producing excited molecules that emitted at 420 nm. The reaction continued as long as the molecules were within the cavity. Electrolysis by direct current was more efficient than alternating current, and reducing the distance between electrodes improved the results. Researchers said spectrum changes measured as a function of intensity clearly showed stimulated emission.