 Gerhard G. Paulus

Gerhard G. Paulus is a physicist whose Jena university profile identifies research in strong-field laser physics, attosecond physics and the absolute phase of very short optical pulses. The profile records a professorship in experimental physics and nonlinear optics beginning in 2007.^[ref]

A motivating experimental question is whether two pulses with the same intensity envelope can drive different electron motion. A simple original field model isIts carrier-envelope phase is $\varphi$. At the envelope maximum $t=0$, choosing $\varphi =0$ gives $E=E_0$, whereas $\varphi =\pi /2$ gives $E=0$. The envelope is unchanged. This distinction is especially consequential for few-cycle pulses and processes that respond to the instantaneous electric field; it does not claim that all detectors resolve the carrier oscillation.

A 2017 account by the collaborating FAU experimental group describes a direct probe of focal phase: photoelectric effect at a nanometer-sharp tip was sensitive to carrier-envelope phase, and the tip was raster-scanned through the laser focus. The account explicitly identifies collaboration with Paulus's Jena group.^[ref]

The important observable is a phase-sensitive electron response, rather than only a light intensity image. A focus can change the relative optical phases through the Gouy phase; for a pulse, the variation of focusing with frequency can also matter. The experiment connects a local material probe to the spatial waveform of a light pulse without assigning every coauthor's experimental step to Paulus individually.