Robert Mitchell

Modeling crater formation in femtosecond-pulse laser damage from basic principles

We present the first fundamental simulation method for the determination of crater morphology due to femtosecond-pulse laser damage. To this end we have adapted the particle-in-cell (PIC) method commonly used in plasma physics for use in the study of laser damage and developed the first implementation of a pair potential for PIC codes. We find that the PIC method is a complementary approach to modeling laser damage, bridging the gap between fully ab-initio molecular dynamics approaches and empirical models. We demonstrate our method by modeling a femtosecond-pulse laser incident on a flat copper slab for a range of intensities.

Modeling femtosecond pulse laser damage using particle-in-cell simulations

Abstract. We present, to our knowledge, the first adaptation of the particle-in-cell (PIC) simulation method for use in the study of femtosecond pulse laser damage, including the first implementation of the Morse pair-potential for PIC codes. We compare the PIC method to a wide variety of currently used modeling schemes, ranging from purely ab initio molecular dynamics simulations to semi-empirical models with many fitting parameters and show how PIC simulations can provide a complementary approach by filling the gap in theoretical methodology between the two cases. We detail the necessity and implementation of an interatomic pair-potential in PIC studies of laser damage. Finally, we use our model to treat the full laser damage process of a copper target and show that our results compare well to simple scaling laws for crater size.

Modeling femtosecond pulse laser damage on conductors using Particle-In-Cell simulations

We present, to our knowledge, the first adaptation of the Particle-In-Cell (PIC) simulation method for use in the study of femtosecond pulse laser damage, including the first implementation of the Morse potential for PIC codes. We compare the PIC method to a wide variety of currently used modeling schemes, ranging from purely ab-initio molecular dynamics simulations to semi-empirical models with many fitting parameters, and show how PIC simulations can provide a complementary approach by filling the gap in theoretical methodology between the two cases. We detail the necessity and implementation of an inter-atomic pair-potential in PIC studies of laser damage. Lastly, we use our model to treat the full laser damage process of a copper target, and show that our results compare well to simple scaling laws for crater size.

First principles simulation of laser-induced periodic surface structure using the particle-in-cell method

We present our results of a fundamental simulation of a periodic grating structure formation on a copper target during the femtosecond-pulse laser damage process, and compare our results to recent experiment. The particle-in-cell (PIC) method is used to model the initial laser heating of the electrons, a two-temperature model (TTM) is used to model the thermalization of the material, and a modified PIC method is employed to model the atomic transport leading to a damage crater morphology consistent with experimental grating structure formation. This laser-induced periodic surface structure (LIPSS) is shown to be directly related to the formation of surface plasmon polaritons (SPP) and their interference with the incident laser pulse.

Single-shot femtosecond laser ablation of copper: experiment vs. simulation

Single 5 and 40 femtosecond, near IR pulses with fluences varying from 0.4 – 80 J/cm2 from a Ti:Sapphire laser was focused onto a single crystal Cu sample surface with 2.0 μm focal spot at 15 and 45 degree angle of incidence. The surface profiles after interaction were studied with an interferometric depth profiler (Wyko NT9100), and benchmarked against crater size and morphology predicted by 2D Particle-In-Cell (PIC) laser damage simulation model.

Using particle-in-cell simulations to model femtosecond pulse laser damage

We present the first fundamental simulation method for the determination of crater morphology from femtosecond-pulse laser damage. To this end we have adapted the Particle-In-Cell (PIC) method for use in the study of laser damage, and developed the first implementation of a pair-potential for PIC codes. We discuss how the PIC method is a complementary approach to modeling laser damage, bridging the gap between fully ab-initio molecular dynamics approaches and empirical models. We demonstrate our method by modeling a femtosecond-pulse laser incident on a flat copper slab, for a range of intensities.