Nanooptics and photonics

Modelling the Optical Properties of Triangular Ag Nanoprisms
Bulavinets T.O.1, Yaremchuk I.Ya.1, Kovalchuk V.I. 1, Bobitski Ya.V.1,2
1 Department of Photonics, Lviv Polytechnic National University,
12, S. Bandera Str., Lviv 79013, Ukraine 
E-mail: tetiana.o.bulavinets@lpnu.ua 
2 College of natural sciences Institute of Physics University of Rzeszow 
Rzeszow, Poland.

Recently, nanoparticles characterized by localized surface plasmon resonance (LSPR) have been actively studied. Research of their physical and chemical properties proceed. The search of new fabricating methods, prospects and possibilities of their application in various branches continues. The study of parameters that affect the optical properties of plasmon nanomaterials and allow controlling and adjusting the LSPR is a very important task. It is known that the critical parameters that affect the position of nanoparticles LSPR peak and are the material, size, shape, structure and parameters of surrounding medium. These parameters of nanomaterials are crucial for possibility of their practical application.
Among the number of plasmon nanostructures in recent years, triangular silver nanoprisms have been actively studied. Modern methods allow to make the triangular nanoprisms with the correct shape and predetermined optical properties with high accuracy. Such structures are interesting due to their ability to exhibit plasmonic properties in the visible and NIR regions of the spectrum and can be used in biomedical and energy applications.
Our interest was in the study of the influence of geometric parameters on the optical response of triangular Ag nanoprisms. Simulation of light absorption efficiency factor of nanotriangles in the visible and NIR range was performed using the DDA method. During the simulation, the edges lengths of the triangular nanoprisms were initially changed from 90 to 350 nm at a constant thickness. The obtained results show that the LSPR peaks had a redshift with increasing edge length of Ag nanoprisms. Moreover, the light absorption efficiency decreased with increasing edge length. In the following study, the edge lengths of the triangular Ag nanoprisms were maintained, while the thickness was changed from 15 to 30 nm. As a result, an increase in the thickness of nanoprisms leads to a blue-shift of the LSPR peaks and a decrease in the light absorption efficiency. Thus, changes in the geometric parameters of triangular Ag nanoprisms cause a change in their optical response. A clear understanding of how size affects the optical properties of triangular silver nanoprisms is important for their effective application.