Document Type : Research
Authors
1 Department of Physics, Faculty of Science, Razi University, Kermanshah, Iran
2 Department of Physics, Faculty of Science, Lorestan University, Khorramabad, Iran
Abstract
A B S T R A C T
In this paper, optical bistability in a Fabry-Pérot optical cavity filled with semiconductor quantum dots coupled to graphene-coated metal nanospheres is investigated due to the outstanding optical properties of graphene, such as its strong nonlinear optical response and strong light-graphene interaction, which have numerous potential applications in optoelectronic devices. In a hybrid molecule made of a semiconductor quantum dot coupled to a graphene-coated nanoparticle structure, the quantum dot is considered as an atomic system, and the Hamiltonian of the system is written under the electric dipole and rotating wave approximations. Then, the dynamic equations of the system are written in the density matrix approach, and Maxwell's equation is used to describe the propagation of the probe field inside the cavity to achieve optical bistability. By solving the density matrix equations in the steady state, and also by applying boundary conditions, the relationship between the incident field and the transmitted field is obtained, which can be used to investigate the output intensity in terms of the input intensity. It should be noted that quantum dot-metal nanoparticle hybrid structures have been of interest in recent years due to their ability to enhance plasmon-exciton interactions; therefore, the addition of graphene coating allows for greater tunability. The effect of nanoparticle size, number density of hybrid molecules, and intensity transmission on optical bistability and its hysteretic behavior is investigated.
Keywords
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