New laser generates extremely short pulses

Researchers at the Swiss Federal Institute of Technology in Zurich(ETH), led by Ursula Keller, Professor at the Institute of Quantum Electronics, have developed a laser that can generate the strongest ultrashort laser pulses to date. With an average output of up to 550 watts, the previous record has been beaten by more than half, ETH explained in a press release. "This record is the result of a long and exciting journey with a lot of interesting laser physics," Keller is quoted as saying in the press release.

The laser emits more than 5 million pulses per second, with an output of up to 100 megawatts. "The combination of even higher performance now achieved with pulse rates of 5.5 megahertz is based on two innovations," explains Moritz Seidel, a doctoral student in Keller's laboratory. For example, the researchers have developed a special arrangement of mirrors in the laser in which the light is extremely amplified without impairing the stability of the laser.

On the other hand, a mirror made of semiconductor material invented by Keller was further developed. This Semiconductor Saturable Absorber Mirror (SESAM) causes the laser to generate short pulses instead of a continuous beam. For the new laser, SESAM was equipped with a thin sapphire window, among other things.

The new technology could improve the processing of materials or precision measurements. According to Keller, the new laser also offers opportunities to make watches even more accurate. "It would be a dream come true if we could use such extremely precise clocks to measure that the constants of nature are not constant after all," says the ETH professor. ce/hs