HV discharges triggered by dual- and triple-frequency laser filaments

T. Produit, P. Walch, G; Schimmel, B. Mahieu, C. Herkommer, R. Jung, T. Metzger, K. Michel, Y.-B. André, A. Mysyrowicz, A. Houard, J. Kasparian, J.-P. Wolf, Optics Express, 11339 (2019) link

Abstract: We study the use of frequency upconversion schemes of near-IR picosecond laserpulses and compare their ability to guide and trigger electric discharges through filamentationin air. Upconversion, such as Second Harmonic Generation, is favorable for triggering electricdischarges for given amount of available laser energy, even taking into account the losses inherentto frequency conversion. We focus on the practical question of optimizing the use of energy froma given available laser system and the potential advantage to use frequency conversion schemes.

Free space publication laser telecommunication through fog

G. Schimmel, T. Produit, D. Mongin, J. Kasparian, and J.-P. Wolf, Optica 5, 1338 (2018) link

Abstract: Atmospheric clearness is a key issue for free space optical communications (FSO). We present an active method to achieve FSO through clouds and fog, using ultrashort high-intensity laser filaments. The laser filaments opto-mechanically expel the droplets out of the beam and create a cleared channel for transmitting high-bit-rate telecom data at 1.55 μm. The low energy required for the process allows considering applications to Earth–satellite FSO and secure ground-based optical communication, with classical or quantum protocols.

Shockwave-assisted laser filament conductivity

E. Schubert, D. Mongin, T. Produit, G. Schimmel, J. Kasparian and J.-P. Wolf, Applied Physics Letters 111, 211103 (2017) link

Abstract: We investigate the influence of ultrashort laser filaments on high-voltage discharges and spark-free unloading at various repetition rates and wind conditions. For electric fields well below, close to, and above the threshold for discharges, we observe remote spark-free unloading, discharge suppression, and discharge guiding, respectively. These effects rely on an indirect consequence of thermal deposition, namely, the fast dilution of ions by the shockwave triggered by the filament at each laser shot. This dilution drastically limits ion-ion recombination and increases the plasma channel conductivity that can still be non-negligible after tens or hundreds of milliseconds. As a result, the charge flow per pulse is higher at low repetition rates.