Irradiation of intense ultrafast laser pulses in glasses can lead to formation of nanogratings whose periods are significantly smaller than the incident irradiation wavelength. The mechanism of the exotic phenomenon is still under hot debate. Here, we access the snapshots of morphologies in the laser affected regions in a porous glass which reveal the evolution of the formation of nanogratings with increasing number of laser pulses. Combined with further theoretical analyses, our observation provides important clues which suggest that excitation of standing plasma waves at the interfaces between areas modified and unmodified by the femtosecond laser irradiation plays a crucial role for promoting the growth of periodic nanogratings. The finding indicates that the formation of volume nanogratings induced by irradiation of femtosecond laser pulses is initiated with a mechanism similar to the formation of surface nanoripples.

Date Published: 4 March 2015
PDF: 9 pages
Proc. SPIE 9350, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XX, 93500G (4 March 2015); doi: 10.1117/12.2076905

Published in SPIE Proceedings Vol. 9350:
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XX
Stephan Roth; Yoshiki Nakata; Beat Neuenschwander; Xianfan Xu, Editor(s)