[21a-A306-1~9] 3.6 Laser processing (formerly 3.7)

[21a-A306-5] Pulse duration dependence of spatio-temporal evolution of plasma channel in silica glass

〇Takumi Koike¹, Yusuke Ito¹, Reina Yoshizaki¹, Guoqi Ren¹, Naohiko Sugita¹ (1.Univ. Tokyo)

Keywords:Laser processing, Plasma channel, Time resolved measurements

Electrons are highly excited in dielectric materials when an intense ultrashort laser pulse is focused and forms a filamentary plasma channel, which has wide applications for the microprocessing of dielectric materials, with excellent chemical and optical properties. However, because of its nonlinearity in the process of light propagation, theoretically predicting the evolution characteristics of the plasma channel is difficult. In this study, we experimentally and numerically evaluated the pulse duration dependence of the spatio-temporal evolution characteristics of the plasma channel using precise time-resolved measurements and time-domain beam propagation method, respectively. The experimental results showed that, as the pulse duration increased, the lifetime of the plasma channel increased and the direction of the plasma channel formation reversed. Numerical analyses has shown that the dominant mechanism of plasma channel formation shifted depending on the pulse duration.