Stimulated Brillouin scattering in dispersed graphene

TL;DR

This study investigates how graphene nanoflakes influence Stimulated Brillouin scattering (SBS) in liquids, revealing SBS quenching effects useful for nanoparticle detection and laser technology applications.

Contribution

It reports the first measurement of the Brillouin gain factor in NMP and demonstrates SBS suppression by graphene, enabling nanoparticle detection and SBS control in optical systems.

Findings

Measured SBS energies in NMP and water at 532 nm.

Reported a new Brillouin gain factor for NMP: 18.6 ± 1.8 cm/GW.

Demonstrated SBS quenching by graphene nanoflakes and its potential for nanoparticle detection.

Abstract

We address the problem of the interaction of powerful laser radiation with a transparent substance containing a low concentration of strongly absorbing nanoparticles under the condition of Stimulated Brillouin scattering (SBS) whose behavior in such media was unexplored. SBS energies in N-methyl-2-pyrrolidone (NMP) and water are measured at the wavelength of 532 nm. An experimental value $g_B = 18.6 \pm 1.8$ cm/GW for a previously unknown Brillouin gain factor of NMP is reported. A strong SBS quenching in the liquids by graphene nanoflakes is found. SBS threshold linear dependences on graphene absorption coefficient (concentration) are established and found suitable for the detection of small nanoparticles quantities in water with a minimal detectable concentration of $5 \cdot 10^{-8}$ g/ml. The effect is considered through an electrostriction - thermal expansion antagonism induced by carbon vapor bubbles formation. It is found to be very sensitive to changes in density, refractive index and acoustic absorption coefficient. Using the SBS method, their determination and the bubbling nanosecond time-scaling can be performed. The effect is advantageous for SBS suppression when it is undesirable in laser technologies and optical telecommunication networks.