Regular Article

Optimizing the optical absorption coefficient of a core/shell quantum dot near a bimetallic nanoparticle

¹ Department of Physics, College of Science, Shiraz University, Shiraz 71454, Iran
² Department of Physics, Shiraz University of Technology, Shiraz 313-71555, Iran

^a e-mail: keshavarz@sutech.ac.ir

Received: 22 December 2019
Received in final form: 30 March 2020
Published online: 16 June 2020

Abstract

In this paper, the optical absorption coefficient of a core/shell quantum dot near a bimetallic nanoparticle is maximized. For this purpose, the Schrödinger equation is solved by numerical methods to obtain the exciton energy. Then by using the density matrix method, the absorption coefficient of the hybrid system is calculated. Afterward, by applying the particle swarm optimization (PSO) algorithm, the absorption coefficient of the system is optimized. After obtaining the optimum structure, the refractive index changes, the electric field enhancement factor for the core/shell quantum dot, and the near-field enhancement for the bimetallic nanoparticle are examined. Additionally, the optical absorption coefficient is calculated for different radii of the bimetallic nanoparticle and for different distances between the surfaces of the core/shell quantum dot and the bimetallic nanoparticle. Then it is compared with that of the optimum structure. The results show that the absorption coefficient of the optimum structure is 3.41 × 10⁶ (m⁻¹) and its electric field enhancement increases up to 9 times.