Modeling damage formation in copper illuminated by laser pulses of few optical cycle duration using particle-in-cell simulations

Laser damage is important either as something to avoid or for application in medicine and technology. Fundamental modeling of laser damage from room temperature through final re-solidification of the medium is difficult due to the wide array of time scales and physical regimes involved. Traditional particle-in-cell (PIC)¹ simulations are excellent for treating the light-matter interaction self-consistently, however, PIC suffers from an inability to accurately capture the warm dense matter and solid state physics required. We have developed a PIC based method incorporating atomic pair potentials and the two-temperature model that models the entire damage process starting from a room temperature metal target². In this work, we have applied this method to damage formed from intense few-cycle pulses (FCPs). We explore damage for different wavelengths from 400 nm to 1600 nm with a varying number of cycles at constant fluence. We also explore the effect of varying envelope carrier phase. We observe significant variation in the depth of the deposited energy and the subsequent inward flow of energy driven by the strong thermal gradients normal to the target surface. These effects determine the depth of the resulting damage spot.

[1] Welch, D. & Rose, D., Comp. Phys. Comm. 164, 183-188 (2004)

[2] A.M. Russell and D.W. Schumacher, Physics of Plasmas 24, 080702 (2017).