Nonlinear evolution of aluminum surface relief under multiple femtosecond laser irradiation

Abstract

The electromagnetic field interference distribution on the aluminum surface during formation of laser induced periodic surface structures (ripples) under femtosecond laser irradiation is studied. The nonlinear dependence of optical feedback on the geometric parameters of the ripples is shown to play a key role in non linear evolution of the relief with increasing number of pulses. The strongest optical feedback is observed for periods of ripples in the range of Λ = 0.65λ-0.75λ at relief modulation of h = 0.15λ-0.2λ, where λ is the laser wavelength. On the basis of the developed approach, we explain why the frequently observed femtosecond laser induced ripples have similar periods on materials with a high value of the imaginary part and strongly negative real part of permittivity.

Features of changes in the nanostructure and colorizing of copper during scanning with a femtosecond laser beam

“…It is known that during normal incidence of femtosecond, linearly polarized laser pulses, low-spatial-frequency laser-induced periodic surface structures (LSFL) are formed on the copper surface, which demonstrate the effect of diffraction staining [25,26]. That is, the appearance of a surface relief demonstrating properties of a diffraction grating in the visible range is observed.…”

Nanoscale surface boiling in sub-threshold damage and above-threshold spallation of bulk aluminum and gold by single femtosecond laser pulses

“…Femtosecond (fs) laser ablative nano and micro-machining of aluminum (Al), one of the most important construction, electronic, and optoelectronic materials, has been intensively explored during the last two decades [1][2][3][4]. Since the first timeresolved optical reflection studies of the hydrodynamic expansion of supercritical Al fluid in the early 1990s [5], numerous experimental studies have been performed to enlighten its ablation by time-resolved optical microscopy [6], timeresolved optical emission spectroscopy [7], time-resolved ablative shock-wave detection [8][9][10], electric probe diagnostics of prompt plasma [11], and measurements of multi-shot removal rates for different ablation regimes [12].…”