Open AccessLaser induced periodic surface structure formation in germanium by strong field mid IR laser solid interaction at oblique incidence
Author(s) -
Drake Austin,
Kyle Kafka,
Simeon Trendafilov,
Gennady Shvets,
Hui Li,
Allen Y. Yi,
Urszula B. Szafruga,
Zhou Wang,
Yu Hang Lai,
Cosmin I. Blaga,
Louis F. DiMauro,
Enam Chowdhury
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.019522
Subject(s) - laser , optics , surface plasmon polariton , femtosecond , materials science , surface plasmon , germanium , irradiation , excited state , coupling (piping) , plasmon , physics , atomic physics , optoelectronics , silicon , nuclear physics , metallurgy
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.