2025/02/08 by George D. Tsibidis, Matina Vlahou, Tsibidis, George D. +7
Arts and Humanities · Engineering · #Computational Physics (physics.comp-ph) #Cultural Heritage Materials Analysis #Electrohydrodynamics and Fluid Dynamics #FOS: Physical sciences #Laser Material Processing Techniques #Materials Science (cond-mat.mtrl-sci) #Optics (physics.optics)
paper · pdf · doi:10.48550/arxiv.2502.05639
openalex publication_date 2025/02/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Polymers exposed to ultrashort pulsed lasers (UPL) experience a range of physical and chemical changes that play a key role in applications ranging from material processing to advanced photonics, and biomedicine. To elucidate the interaction of UPL with polymeric materials, ultrafast phenomena such as carrier dynamics, recombination and relaxation are investigated assuming polycarbonate (PC) as a test material exposed to laser pulses of moderate energies. A theoretical model developed for dielectric materials is extended to describe the, previously, unexplored excitation and carrier dynamics for PC while femtosecond Transient Absorption Spectroscopy is used to elucidate the evolution of the materials response and ultrafast dynamics. Interpreting the experimental measurements using the theoretical model suggests the existence of an energy level that facilitates the formation of self-trapped exciton metastates between the conduction and valence bands (approximately 2.4-2.8 eV below the conduction band). It also predicts the electron-plasma lifetime (around 110-150 fs), the recombination time (about 34 ps), and the non-linear part of the refractive index due to Kerr effect (with n2 values ranging from (1.1-1.5)x10-16 cm2/W). Furthermore, the dominant character of multi-photon assisted ionisation is emphasised while the optical breakdown threshold is also calculated and found to be equal to 2.55 x1012 W/cm2. The results are expected to support future efforts aimed at elucidating how intense ultrashort laser pulses interact with polymeric materials which is crucial for optimizing the manufacturing processes of these materials for potential applications.