Size Dependence of the Resonant Third-Order Nonlinear Refraction of Colloidal PbS Quantum Dots

Ivan D Skurlov,Evgeniia A Ponomareva,Anastasiia V Sokolova,Azat O Ismagilov,Ilia A Vovk,Aleksandr P Litvin,Sergey E Putilin,Anton N Tcypkin

doi:10.3390/photonics7020039

Ivan D Skurlov, Evgeniia A Ponomareva + Show 6 more

Open Access

https://doi.org/10.3390/photonics7020039

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Journal: Photonics	Publication Date: Jun 1, 2020
Citations: 10	License type: CC BY 4.0

Affiliation: ITMO University

Abstract

Due to their high resonant third-order nonlinear response, lead sulfide quantum dots (QDs) are potential materials for applications in the field of nonlinear optics. In this paper, we implement the Z-scan method to study the resonant nonlinear response of lead sulfide QDs in colloidal solutions. We managed to measure the purely intrinsic resonant nonlinear response, free of thermal contribution. We report that the lead sulfide QD third-order nonlinear response per QD shows an unconventional increase. A figure of merit for QD nonlinearity grows as a power function with a factor of 2.9.

Highlights

Semiconductor quantum dots (QDs) can find their use in nonlinear-optical (NLO) applications due to the spike-like density of their electronic states
We assume that our QDs nonlinear response originates from two counterparts: electronic and thermal
In the resonant case, pumping the sample with a high pulse repetition rate (PRR) laser beam may lead to the appearance of

Summary

Introduction

Semiconductor quantum dots (QDs) can find their use in nonlinear-optical (NLO) applications due to the spike-like density of their electronic states. The concentration of optical transitions in very narrow energy intervals in QDs causes a strong enhancement of the NLO response [1,2]. Confined QDs have been studied in more detail for a variety of materials (such as CdS, CdSe, Ag2 S or CsPbBr3 ) [3,4,5,6]. The available studies of strongly confined QDs are mostly limited to PbSe and PbS [7,8]. NLO effects should be more pronounced in QDs, which are in a strong confinement regime. In this regime, both electrons and holes are confined, and optical transitions occur between single-particle eigenstates, concentrating the optical transitions in a single energy interval. Absolute changes in the refractive index can be large before the saturation of the transition [11]

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