Plasma waves excited at interface by femtosecond laser irradiation enabling formation of volume nanograting in glass

TL;DR

This study investigates how femtosecond laser pulses induce plasma waves at glass interfaces, leading to the formation of sub-wavelength nanogratings, and provides new insights into the underlying mechanism of nanograting development.

Contribution

It reveals that standing plasma waves at interfaces are crucial for nanograting formation, offering a new understanding of the process in porous glass.

Findings

Nanogratings evolve with increasing laser pulses.

Standing plasma waves are key to nanograting growth.

Volume nanogratings form via a mechanism similar to surface nanoripples.

Abstract

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 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.