Diffraction based single pulse measurement of air ionization dynamics induced by femtosecond laser

Abstract

A single pulse diffraction method to probe the plasma column evolution of the air ionization induced by the femtosecond laser pulse has been proposed. By utilizing a linearly chirped pulse as the probe light, the spatiotemporal evolution spectrum of the plasma column can be acquired in a single measurement. A method based on the Fresnel diffraction integral is proposed to extract the evolution of the phase shift after the probe light is crossing through the plasma column. Results show that the plasma expands rapidly within 7 ps due to the ionization, and then reaches a steady state with a diameter of about 80 μm with the pump pulse energy of 1 mJ. Furtherly, the temporal profile of the free electron density and the refractive index in the plasma region were determined using the corresponding physical models. The single-shot method can be expected to broaden the way for detecting the dynamics of the femtosecond laser-induced plasma.

Layer-dependent photoexcited carrier dynamics of WS2 observed using single pulse pump probe method

“…The schematic diagram of the proposed single pulse pump probe method is shown in Fig. 2(a), which is similar to the configuration in our previous work [29] . A Ti:sapphire laser (Newport Corporation, SOL-ACE35F1K-HP) is employed to deliver 35 fs Gaussian limit pulses with central wavelength of 800 nm and maximum single pulse energy of ∼7 mJ.…”

“…It is well known that, in the measurement of dynamic processes on ultrafast time scales, the reported methods include multi-shot methods [11,13,17,28] and single-shot methods [29][30][31] . In the measurements of photoexcited carrier dynamics, due to the instability of the output pulse and the inhomogeneity of the sample, non-negligible uncertainties and systematic errors to the results will be inevitably introduced from the data collected in different shots.…”