Controlling the Pump-Probe Optical Response in Asymmetric Tunneling-Controlled Double Quantum Dot Molecule—Metal Nanoparticle Hybrids

Spyridon G Kosionis,Emmanuel Paspalakis

doi:10.3390/app112411714

Abstract

In the present work, we investigate the modified nonlinear pump-probe optical properties due to the excitonic–plasmonic interaction of a double semiconductor quantum dot (SQD) molecule coupled to a metal nanoparticle (MNP). More specifically, we study the absorption and the dispersion spectra of a weak electromagnetic field in a hybrid structure with two counterparts, a molecule of two coupled SQDs, and a spherical MNP driven by a field of high intensity. We solve the relevant density matrix equations, calculate the first-order optical susceptibility of the probe field in the strong pumping regime, and investigate the way in which the distance between the two counterparts modifies the optical response, for a variety of values of the physical constants of the system, including the pump-field detuning, the tunnelling rate, and the energy separation gap associated with the excited states of the coupled SQDs.

Highlights

In current studies in photonics, coupled structures formed from semiconductor quantum dots and metal particles at the nanoscale play an important role as they give, in many cases, enhanced optical properties in comparison to individual SQDs and metal nanoparticle (MNP) [1]
These effects can find applications in the construction of efficient optical devices which can be implemented in the fields of nanophotonics and quantum technology. In some of these studies, the nonlinear optical effects in an SQD-MNP hybrid structure are examined under interaction with a pump field of high intensity and a tunable probe field of much lower intensity [7,18,23,24,26,28,34,36]
ResulHtsere, we investigate the characteristics associated with the absorption and the dispersion spectra of a probe field applied to an SQD-MNP hybrid structure, under the interaction wiHtheraes,trwoneginpvuemstpigfiaeteld,thfoer cvhaariroauctseirnistteircpsaratsiscolecidaitsetdanwceist.hInthteheafboslolorwptiinognpaanradgrtahpehs, diswpeercsoionnsisdpeercatrlainoefaralypprooblaerifzieelddsatpropnligedputmo panfiSelQdD

Summary

Introduction

In current studies in photonics, coupled structures formed from semiconductor quantum dots and metal particles at the nanoscale play an important role as they give, in many cases, enhanced optical properties in comparison to individual SQDs and MNPs [1]. The coupling of the excitons to plasmons is responsible for the emergence of interesting optical effects from the SQD-MNP structures, including altered excitonic Rabi oscillations [2,3,4], creation and control of optical bistability and multistability [5,6,7,8,9], population transfer to the exciton [10,11,12,13,14] or biexciton state with high accuracy [15,16,17], controlled slow light [18], creation of gain without inversion [19,20,21], strong enhancement of second harmonic generation [22], and strong modification of four-wave mixing, as well as self- or cross-Kerr nonlinearity [23,24,25,26], control of resonance fluorescence [27,28,29,30], and several others [31,32,33,34,35,36,37,38] These effects can find applications in the construction of efficient optical devices which can be implemented in the fields of nanophotonics and quantum technology.

Methods

Results

Conclusion