Impact of SiO$_2$ nanoparticle morphology on scattering efficiency for random lasers

TL;DR

This study compares crystalline and amorphous silica nanoparticles as scatterers in a random laser, demonstrating that crystalline QtzNPs enhance laser efficiency due to higher refractive index and morphology effects, supported by experiments and FEM simulations.

Contribution

It reveals how nanoparticle morphology and refractive index influence scattering efficiency in random lasers, providing insights for optimizing laser performance with nanomaterials.

Findings

QtzNPs increase RL efficiency more than ASNPs at low concentrations.

Higher RI of QtzNPs enhances light reflectance and scattering.

FEM simulations confirm experimental observations of morphology effects.

Abstract

In this work, we compared the effect of Quartzite nanoparticles (QtzNP - crystalline SiO$_2$) and amorphous silica nanoparticles (ASNP) as scatters in a random laser (RL), correlating the laser efficiency to the morphology and refractive index (RI) of the scatterers. The RL was based on a laser media containing suspensions of QtzNPs or ASNPs in Rhodamine 6G (Rh6G) and ethylene glycol (EG) suspension. It was observed a considerable increase in RL efficiency for QtzNPs, as compared to ASNPs, even for concentrations as low as 0.5mg/mL. Such grow in the RL eficiency is attributed to the higher RI of QtzNPs (n=1.54), which in-creases the reflectance of light on the particles surface and the high field scattering intensity in the sharp edges of the flat slab shapes, associated to the particle's morphology. Finite Element Method (FEM) simu-lations were also performed for different particle size and shapes and an output increase is noticed for QtzNPs when compared with the ASNP confirming the experimental results. The comparison between the morphology of QtzNPs and ASNPs on scattering efficiency reported here contribute to optimize the performance of laser systems with natural and synthetic nanomaterials.