TITLE:
In the Heart of Femtosecond Laser Induced Nanogratings: From Porous Nanoplanes to Form Birefringence
AUTHORS:
R. Desmarchelier, B. Poumellec, F. Brisset, S. Mazerat, M. Lancry
KEYWORDS:
Silica, Glasses, Nanoporous, Femtosecond Laser Processing, Birefringence, Nanogratings
JOURNAL NAME:
World Journal of Nano Science and Engineering,
Vol.5 No.4,
November
13,
2015
ABSTRACT: It is demonstrated that the form birefringence related to the so-called nanogratings is quantitatively correlated to the porosity-filling factor of these nanostructures. We reveal that matters surrounding the nanopores exhibit significant refractive index decrease which is likely due to the fictive temperature increase and/or the presence of a significant amount of interstitial O2. The control of the porosity was achieved by adjusting the laser pulse energy and the number of pulses/micron i.e. the overlapping rate. Applications can be numerous in fast material processing by the production of nanoporous matter, and photonics by changing the optical properties.