Domenikou Natalia, Kosionis Spyridon G, Thanopulos Ioannis, Yannopapas Vassilios, Paspalakis Emmanuel
Materials Science Department, School of Natural Sciences, University of Patras, 26504 Patras, Greece.
Department of Physics, School of Natural Sciences, National Technical University of Athens, 15780 Athens, Greece.
Micromachines (Basel). 2023 Sep 4;14(9):1735. doi: 10.3390/mi14091735.
We investigate theoretically the optical response of a zinc-phthalocyanine molecular quantum system near a gold spherical nanoparticle with a radius of 80 nm. The quantum system is irradiated by a strong pump and a weak probe coherent electromagnetic field. Using the density matrix methodology, we obtain analytical expressions for the absorption, dispersion, and the four-wave-mixing coefficients. The influence of the nanoparticle on the spontaneous decay rate of the quantum system, as well as on the external fields, are obtained by an electromagnetic Green's tensor method. The spectroscopic parameters of the molecule are also obtained by ab initio methods. For the studied optical spectra, we find that, below a critical distance between the molecule and the plasmonic nanoparticle, determined by the minimal value of the effective Rabi frequency, single-peaked spectra are observed. Above this critical distance, the spectra exhibit the characteristic Mollow-shaped profiles. The enhancement of the pump field detuning induces the shift of the sideband resonances away from the origin. Lastly, and most importantly, regardless of the value of the detuning, the optical response of the system is maximized for an intermediate value of the interparticle distance.
我们从理论上研究了半径为80纳米的金球形纳米颗粒附近锌酞菁分子量子系统的光学响应。该量子系统受到强泵浦和弱探测相干电磁场的照射。使用密度矩阵方法，我们得到了吸收、色散和四波混频系数的解析表达式。通过电磁格林张量方法得到了纳米颗粒对量子系统自发衰变率以及对外场的影响。分子的光谱参数也通过从头算方法获得。对于所研究的光谱，我们发现，在由有效拉比频率的最小值确定的分子与等离子体纳米颗粒之间的临界距离以下，观察到单峰光谱。在这个临界距离以上，光谱呈现出特征性的莫洛形状轮廓。泵浦场失谐的增强导致边带共振从原点移开。最后，也是最重要的，无论失谐值如何，系统的光学响应在粒子间距离的中间值时最大化。
