A study is proposed creatively on the strong and weak coupling properties of plasmon coupling systems in both frequency domain and time domain. Theoretically, calculations on the eigen-frequencies, decay rates and the evolutions of bright and dark mode with respect to the strength of coupling under a certain system are performed. Numerically, in the frequency domain calculations on the features of hybridized modes and scattering spectrum and also the splitting phenomenon of bright and dark modes are performed. In the time domain, the periodicity of the beat pattern from the hybridized modes with a difference in frequency is utilized to determine the precise eigen-frequencies of the hybridized modes. From the time domain calculations, the precise eigenfrequencies are close but do not absolutely correspond to the two peaks of the scattering spectrum. By sweeping the coupling distance and measuring the mode evolution, the area where the exceptional point exists is found and specified by fitting to the frequency domain response. In the weak coupling domain, time domain calculations show as expected that both the bright mode and dark mode decay with their individual decay rates.

%U http://xbna.pku.edu.cn/EN/10.13209/j.0479-8023.2019.026