Femtosecond laser dynamics in Kerr nonlinear transparent materials influenced by avalanche ionisation, radiative recombination, and electron diffusion mechanisms
A talk in the SPDEvent series by
Kameni Nteutse Peguy from AIMS Senegal
| Abstract: | Femtosecond lasers interacting with Kerr nonlinear optical materials, propagate in form of filaments due to the balance of beam diffraction by self-focusing induced by the Kerr nonlinearity. Femtosecond laser filamentation is a universal phenomenon that belongs to a general class of processes proper to ultrashort lasers processing systems, associated with the competition between nonlinearity and dispersion also known to promote optical solitons. In this work, we investigate the femtosecond laser inscription process in transparent Kerr media, focusing on the complex dynamics driven by plasma generation and evolution. The system is modelled by a cubic complex Ginzburg–Landau equation incorporating a K-order nonlinear term to represent multiphoton absorption, coupled with a first-order nonlinear ordinary differential equation governing the temporal evolution of the electron plasma density. This model accounts for key physical mechanisms, including avalanche ionisation, radiative recombination, and electron diffusion. Through detailed numerical simulations, we analyse how the competition among these processes shapes the temporal profiles of the laser field and plasma density. Notably, we find that higher-order multiphoton ionisation and the inclusion of electron diffusion significantly influence the laser dynamics during inscription process. These findings provide insights into the stability and control of femtosecond laser inscription in nonlinear media and open pathways for engineering structured light-matter interactions in advanced photonic applications. |