Dear colleagues and friends of the HI-Jena,

Welcome to the autumn issue of our newsletter. Below you find informations about the latest news and activities of our institute

Kind Regards,
Helmholtz Institute Jena

Broadband coherent light sources are used in a wide range of applications today. Examples include ophthalmology, telecommunication, femtochemistry, attosecond-science and light-driven electronics. In almost all applications theses light pulses are focused. Researchers of the Helmholtz Institute Jena together with the Friedrich-Alexander University Erlangen have now shown that for broad bandwidth few-cycle light pulses the optical phase behaves very different from the well-known and commonly used Gouy phase, which has been known for more than 100 years and describes the phase evolution of monochromatic focused light beams [1]. The optical phase evolution was measured by virtue of laser-induced electron emission and rescattering from a nanometre sharp metal tip, which is raster-scanned through the focus of a pulsed femtosecond laser beam. In this way, a temporal resolution on the order of attoseconds (10^-18 s) and a spatial resolution on the order of nanometres (10^-9 m) is achieved. The experimental results can be explained by theoretical calculations [2] and were published recently in Ref. [3]. From these findings, conclusions can be drawn about how to manipulate the focal phase in order to steer and control the ultrafast interactions between light and matter and will make it possible to control electron dynamics and chemical reactions by facilitating novel spatial phase distributions [4]. These insights into fundamental physics will further the development of new radiation sources and the field of light wave electronics.

References:
[1] Gouy, L. G. Sur une propriété nouvelle des ondes lumineuses. C. R. Acad. Sci. Paris 110, 1251–1253 (1890).
[2] Porras, M. A. Characterization of the electric field of focused pulsed Gaussian beams for phase-sensitive interactions with matter. Opt. Lett. 34, 1546–1548 (2009).
[3] Hoff D, Krüger M, Maisenbacher L, Sayler AM, Paulus GG, Hommelhoff P, Tracing the phase of focused broadband laser pulses, Nat. Phys. 13 947 – 51 (2017).
[4] Hoff D, Krüger M, Maisenbacher L, Paulus GG, Hommelhoff P, Sayler AM, Using the focal phase to control attosecond processes, J. Opt. (2017).