| Laureate Prof. Dr. Ursula Keller, Swiss Federal Institute of Technology Zurich (ETH), Switzerland Title of work: | |||||||||||
| In the early 1990s, ultrashort laser pulses provided scientists new insights into details of very fast processes. Previously unthinkable applications in measuring technology, medicine and material processing became conceivable. SESAM is now the groundwork for the use of ultrafast pulse lasers in industrial applications. Laser physicists refer to pulses as ultrashort only when light pulses last less than a millionth of one hundredth of a second. | ||||||||||
| They are faster than the typical duration of the interaction between particles: while the material exposed to an ultrashort laser pulse evaporates, the edge remains cold.
Ultrashort pulses are generated with an optical effect called "mode coupling." The light is not switched on and off, but rather fast pulses occur automatically as a result of a special superimposition of laser light waves: the modes. So far many optical elements are required to realize mode coupling. Ultrashort lasers were therefore usually sensitive and could only be used in laboratory conditions.
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The SESAM – SEmiconductor Saturable Absorber Mirror – by Professor Dr. Ursula Keller is a simple optical element used to activate mode coupling. This saturable absorber mirror is made of overlaid semiconductor layers. It has the special property of generating ultrashort pulses simply and reliably. All that is required is to install it as the mirror in appropriate lasers.
With the invention of the SESAM, Professor Dr. Ursula Keller has made it possible to bring the ultrafast laser out of the laboratory. |
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| In the meantime, SESAMs are being used in commercial beam sources around the world. In 1994, Professor Keller and her husband, Dr. Kurt Weingarten, founded the company Time-Bandwidth Products to market the SESAM, which she patented and trademarked. Prof. Dr. Ursula Keller is a full professor of experimental physics and the head of the Ultrafast Laser Physics Laboratory at Swiss Federal Institute of Technology (ETH), Zurich, Switzerland. She receives first prize for the development of SESAM mirrors, which she invented in 1992 at Bell Labs in the U.S.A. and then further developed experimentally and theoretically at ETH. | |||||||||||
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