Sub-1 V/cm E-FISH-based picosecond electric field measurements in atmospheric pressure air

We report on the development of a highly sensitive electric field induced second harmonic generation diagnostic setup capable of measuring electric field strengths as low as 1 V cm − 1 at the picosecond time scale under atmospheric pressure conditions. This unprecedented sensitivity is achieved through passive homodyne detection, which utilizes stray signals generated by an optical component in the beam path. Our detection limit of 0.3-0.5 V cm − 1 represents an improvement of over 2-3 orders of magnitude compared to previous reports (100-1000 V cm − 1 ) in the literature. Additionally, we demonstrate sensitivity to the polarity of the electric field. Experimental results are corroborated by simulations of the 400 ps time-resolved homodyne process, offering deeper insights into the enhanced detection capabilities and the system’s ability to resolve the field sign.