Pulse repetition-rate effect on the intensity inside a femtosecond laser filament in air

Abstract

As intense, ultrashort, kHz-repetition-rate laser systems become commercially available, pulse cumulative effects are critical for laser filament based applications. In this work, the pulse repetition rate effect on the femtosecond laser filamentation in air was investigated both numerically and experimentally. The pulse repetition rate effect has negligible influence at the leading edge of filament. Clear intensity enhancement from high repetition pulse is observed at the peak and tailing edge of laser filament. As the repetition rate of the laser pulses increasing from 100Hz to 1000Hz, the length of filament extends and the intensity inside the filament increases. A physical picture based on the pulse repetition

An Experimental Determination of Critical Power for Self-Focusing of Femtosecond Pulses in Air Using Focal-Spot Measurements

“…Furthermore, the N 2 and O 2 molecules in excited states or thermal waveguide structures induced by laser pulses may have an impact on the subsequent pulses [12,54], and also on the determination of critical power for self-focusing. The complex dynamics can be revealed through the manipulation of the laser repetition frequency, which requires further studies.…”

Pulse repetition rate effect on the plasma inside femtosecond laser filament in air

“…So far, the plasma density and electron temperature inside the filaments in air have been measured and analyzed mostly in the case of air excitation by the femtosecond laser pulses under a single repetition rate [16][17][18] . Recently, laser repetition-related THz production [11] , wake dynamics [19] , fluorescence [20] , clamping intensity [21] , and the cumulative effects [22] from air filaments have been reported as high-energy, ultrashort, high-repetition-rate laser systems become commercially accessible. Through pump-probe experiments [23] , we recently found that the low-density region, due to the accumulative effect by 1 kHz repetition filaments, results in higher plasma density obtained in the measurements.…”