In this thesis, we investigate the strong coupling between plasmon and exciton. Coupling between metal nanoparticle and emitter causes the creation of polariton modes called plexitons and the formation of a depression between them (metal nanoparticle and emitter).
For this purpose, we design and model several different structures that have the ability to excite plasmonic modes and coupling between these modes. The time domain finite difference method has been used to model the interaction of light with these structures. In this way, absorbing boundary conditions are considered around the structure and the total field/scattered field technique is used for the incident plane wave in the wavelength range of 600 to 1400 nm. To obtain the scattering cross-section, a suitable detector is placed around the structure, and Drude and Lorentz models are used to describe the optical properties of plasmonic metals (gold and silver) and pigment molecules.
Examining the results shows that factors such as the type of nanoparticle, the refractive index of the surrounding environment and the size of the nanoparticle have an effective role on the surface plasmons and on the coupling and placement in the strong or weak region. Examining the two parameters oscillator power and damping coefficient in the Lorentz model for pigment shell or quantum dot shows that increasing the oscillator power and decreasing the damping coefficient is effective in sharpening the depression formed due to coupling and causes strong coupling. It can be We also show that the presence of the shell plays an important role in increasing the range of surface plasmons.
In the following, we will examine the sensitivity of two nanowire and oval structures and finally come to the conclusion that the oval structure with a sensitivity of 4.4 is more sensitive than the nanowire structure with a sensitivity of 1.1. We also investigate the effect of the quantum dot on the plasmon-exciton coupling, which despite the sharp