A transmission electron microscopy study of nanogratings formed in bulk amorphous silica by direct writing with an ultrafast pulsed laser with a radiation wavelength of 1030 nm and pulse duration of 560 fs is presented. The results achieved show that the nanogratings are composed of planar nanostructures with an average periodicity of 250 nm and typical thickness of about 30 nm, consisting of alternating layers of heavily damaged material and layers of material where a dense precipitation of nanocrystals occurred. The crystallization of silica to form these nanocrystals can be explained by the large pressures and temperatures reached in these regions as a result of nanoplasma formation and recombination.
© 2013 Optical Society of America
Original Manuscript: September 10, 2013
Revised Manuscript: October 24, 2013
Manuscript Accepted: October 25, 2013
Published: November 20, 2013
Vitor Oliveira, Sahendra P. Sharma, Pilar Herrero, and Rui Vilar, "Transformations induced in bulk amorphous silica by ultrafast laser direct writing," Opt. Lett. 38, 4950-4953 (2013)