scholarly journals Optical Multistability in the Metal Nanoparticle–Graphene Nanodisk–Quantum Dot Hybrid Systems

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1687 ◽  
Author(s):  
Mariam M. Tohari ◽  
Moteb M. Alqahtani ◽  
Andreas Lyras

Hybrid nanoplasmonic systems can provide a promising platform of potential nonlinear applications due to the enhancement of optical fields near their surfaces in addition to the control of strong light–matter interactions they can afford. We theoretically investigated the optical multistability of a probe field that circulated along a unidirectional ring cavity containing a metal nanoparticle–graphene nanodisk–quantum dot hybrid system; the quantum dot was modeled as a three-level atomic system of Lambda configuration interacting with probe and control fields in the optical region of the electromagnetic spectrum. We show that the threshold and degree of multistability can be controlled by the geometry of the setup, the size of metal nanoparticles, the carrier mobility in the graphene nanodisk and the detunings of probe and control fields. We found that under electromagnetically-induced transparency conditions the system exhibits enhanced optical multistability with an ultralow threshold in the case of two-photon resonance with high carrier mobility in the graphene nanodisk. Moreover, we calculated the limits of the controllable parameters within which the switching between optical multistability and bistability can occur. We show that our proposed hybrid plasmonic system can be useful for efficient all-optical switches and logic-gate elements for quantum computing and quantum information processing.

2012 ◽  
Vol 25 (4) ◽  
pp. 045304 ◽  
Author(s):  
Spyridon G Kosionis ◽  
Andreas F Terzis ◽  
Seyed M Sadeghi ◽  
Emmanuel Paspalakis

2019 ◽  
Vol 17 (2) ◽  
pp. 131-144
Author(s):  
Vladan Pavlovic ◽  
Zeljko Laic ◽  
Ljiljana Stevanovic ◽  
Nikola Filipovic

In this paper, we investigated the realization of electromagnetically induced transparency (EIT) in a rectangular quantum dot (QD) with a single electron in the presence of probe and control laser fields. The lowest three levels of the confined electron that form ladder and V configuration were chosen. We discussed the dependence of density matrix elements for ladder configuration and for V configuration on detunings of the probe field for various values of quantum dot dimensions. This dependence is discussed for both cases, at cryogenic temperatures when spontaneous emission dominates the relaxation mechanism and at room or higher temperatures when dephasing rate cannot be neglected.


2021 ◽  
Vol 11 (24) ◽  
pp. 11714
Author(s):  
Spyridon G. Kosionis ◽  
Emmanuel Paspalakis

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.


2016 ◽  
Vol 14 (1) ◽  
pp. 1-7
Author(s):  
Vladan Pavlovic ◽  
Ljiljana Stevanovic

The present paper analyzes the group velocity of light in a ladder-type spherical quantum dot with on-center hydrogenic impurity. The three level ladder configuration is realized by energy levels of hydrogenic impurity, together with the probe and control laser fields. Group velocity of the probe field is then investigated as a function of the spherical quantum dot radius, probe field frequency, and control laser field intensity.


2010 ◽  
Vol 24 (20) ◽  
pp. 2151-2160
Author(s):  
ZHI-PING WANG ◽  
SHUANG-XI ZHANG

We show the steady-state optical multistability (OM) behavior in a four-level atomic system inside a unidirectional ring cavity. We find that the intensity and the detunings of the fields can affect the optical multistability behavior dramatically, which can be used to control the transition from OM to OB or vice versa without the need to resort to the effect of spontaneously generated coherence (SGC). The effect of the atomic cooperation parameter on OM is also studied. Our scheme may be used for building more efficient all-optical switches and logic-gate devices for optical computing and quantum information processing.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1774 ◽  
Author(s):  
Dongting Wang ◽  
Shangheng Liu ◽  
Mingfa Shao ◽  
Jinghan Zhao ◽  
Yukun Gu ◽  
...  

Hierarchical SnO2 nanocrystallites aggregates (NAs) were prepared with a simple room temperature–based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO2 NAs were subsequently combined with SnO2 nanosheet–based structures from the viewpoint of a function-matching strategy, and under an optimized condition, a power conversion efficiency (PCE) of 5.59% was obtained for the resultant hybrid photoanode, a remarkable 60% enhancement compared to that of dye-sensitized solar cells (DSCs) fabricated with bare SnO2 NAs architecture. The significantly enhanced efficiency can be attributed to the combination of the desirable electron transport property obtained by the intentionally introduced SnO2 nanosheets (NSs) and the effectively retained inherent characteristics of SnO2 NAs, i.e., large surface area and strong light-scattering effect. This work provides a promising approach for the rapid development of highly efficient SnO2 photoanode film-based DSCs with the properties of simplicity of operation and control over the photoanode composition.


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