The Optical Characteristics For The Nanoporous Gold Structures Coupled With Quantum Dots

The ubiquitous Light-“matter” coupling in physics forms hybrid states with new characteristics processed by neither of the uncoupled constitute states, which leads to a wide range of potential applications in fields of novel optical devices and materials and inspires the persistent research interests and attentions. The coupling between light and "matter" is jointly determined by both the interaction strength and the dissipative energy of the system. In principle, light-“matter” coupling can be divided into two categories: the weak coupling and the strong coupling. In the weak coupling regime, fluorescence enhancement, Raman scattering enhancement, and spontaneous emission enhancement effect can be observed. In the strong coupling regime, lineshapes akin to electromagnetically induced transparency(EIT) have attracted much attention. Inspired by this interactions, researchers have developed new devices such as optical resonators, biosensors, as well as new optical materials. In recent years, due to the richness of the optical properties found in nanostructured systems, the light-“matter” coupling researches in fields of atomic physics has already been extended to nano regime.In this paper, we select nanoporous metal structure with Cd Se quantum dot research system in line with their mutual coupling. Light through the excitation of localized surface of nanoporous gold plasmon modes and surface plasmon polariton modes interact with quantum point of this "substance". Through artificial regulation, we implemented this system in the weak and strong coupling, completed a study on the conversion of the strength of the coupling, the system analyzes the optical properties of the composite under different circumstances coupled system, contact the distinction between strong and weak coupling and the possible applications.Specifically, we conduct our work in three parts: Firstly, using extinction spectroscopy and fluorescence spectroscopy, we have studied the influence of factors which occur weak and strong coupling between quantum dots and surface plasmons. The results show that the coupling behavior of the composite system is strongly dependent on the number of quantum dot, the incident light intensity, and a quantum dot deposition position nanoporous gold structure; secondly, weak coupling, we found the fluorescence emission efficiency of quantum dots will be enhanced, the maximum fluorescence enhancement ratio reaches 4.3 times; Thirdly, unlike the weak coupling, the strong coupling phase, the composite structure can produce electromagnetic induced transparency effect, that the extinction spectra of features split. Particularly interesting is that we found the strong coupling of quantum dots can be modulated fluorescence emission peak position and color, wavelength modulation range of the maximum of 40 nm. According to this feature, we conducted a study for the ultrasensitive detection of hemoglobin molecules in the strong coupling phase.