Laser induced periodic surface structure formation in germanium by strong field mid IR laser solid interaction at oblique incidence

Abstract

Laser induced periodic surface structures (LIPSS or ripples) were generated on single crystal germanium after irradiation with multiple 3 µm femtosecond laser pulses at a 45° angle of incidence. High and low spatial frequency LIPSS (HSFL and LSFL, respectively) were observed for both s- and p-polarized light. The measured LSFL period for p-polarized light was consistent with the currently established LIPSS origination model of coupling between surface plasmon polaritons (SPP) and the incident laser pulses. A vector model of SPP coupling is introduced to explain the formation of s-polarized LSFL away from the center of the damage spot. Additionally, a new method is proposed to determine the SPP propagation length from the decay in ripple depth. This is used along with the measured LSFL period to estimate the average electron density and Drude collision time of the laser-excited surface. Finally, full-wave electromagnetic simulations are used to corroborate these results while simultaneously offering insight into the nature of LSFL formation.

High spatial frequency laser induced periodic surface structure formation in germanium by mid-IR femtosecond pulses

“…The latter value was taken from Austin et al 17 and corrected for the Kerr effect, which was not considered in that paper. It should be noted that this expression for Kerr does not assume Kerr << n 2 0 as was done by Dufft et al 19 .…”

“…used to explain observed properties of LSFL 17,18 . For sand p-polarized light, the respective LIPSS periods predicted by this SPP model are given by…”

Ultra-fast bandgap photonics in mid-IR wavelengths

“…al. [14] revealing the formation of both low (spatial period,   /2) and high spatial frequency ( < /2) LIPSS (LSFL and HSFL, respectively) in germanium at 3000 and 3600 nm, generated by a KTA based 90 fs home-built optical parametric amplifier system (OPA) pumped by a kHz Ti:Sapphire system. Femtosecond MIR interaction can generate a wide range of periodic structures on semiconductors, as shown in Figures 2 and 3.…”

Particle-in-cell simulations of electron acceleration from relativistic interaction of mid-infrared laser interactions with near solid density matter

“…8 Another interesting value of intense mid-IR interactions is in examining the physics of laser damage. 9,10 To the best of our knowledge, despite recent interest in mid-IR ultra-intense laser interactions, the literature has not focused much attention on short-pulse, intense mid-IR laser interactions with dense (i.e., solid or liquid density) targets.…”