Prof Ursula Keller, ETH Zurich
"Ultrafast Solid-State Lasers: Hitting Harder and Faster "
4.15 pm, 2nd November 2006
Scott Russell Building Room SR 3.20, Heriot-Watt University
Abstract
Since 1990 we have observed a tremendous progress in ultrashort pulse generation using passively modelocked solid-state lasers based on novel saturable absorbers such as Kerr lens modelocking (KLM) and semiconductor saturable absorber mirrors (SESAMs). Previously, Q-switching instabilities prevented stable passive modelocking of solid-state lasers for more than 25 years. Today we are able to generate ultrashort pulses of only around two optical cycles (i.e. ≈5 fs pulse duration) directly from KLM Ti:sapphire lasers. This opens up a completely new regime where the exact position of the electric field underneath the pulse envelope (i.e. the carrier envelope offset – CEO) in nonlinear optics has become important and relevant. KLM however has significant limitations, since it is generally not self-starting, and critical cavity alignment close to the stability limit is required. Thus, passively modelocked solid-state lasers using intracavity SESAMs have become a very attractive alternative to KLM, and are more widely used in the above 10-fs regime today. In addition, SESAM modelocked solid-state lasers have increased pulse energy by three orders of magnitude, up to ≈5 µJ, and increased pulse repetition rates by more than two orders of magnitude, to 160 GHz at an operation wavelength around 1 µm and 77 GHz around 1.55 µm. Extending this technique to semiconductor lasers has pushed their performance into the multi-watt level based on new concepts and devices. |
Biography:
To be updated. |