溶剂折射率对Rh6G液体随机激光输出特性的影响

Dependence of the Rh6G Random Laser Behavior on Different Refractive Indices of Solvent

通过选择甲醇、乙醇、乙二醇和二甲亚砜四种不同折射率液体作为溶剂溶解分散掺杂有尺寸为100nm的AlN纳米粒子的罗丹明6G(Rh6G)激光染料,制备出了不同折射率溶剂的Rh6G随机激光体系。分别测量了这些体系的随机激光光谱和阈值,研究了在溶剂的折射率不同的随机激光体系中光谱、阈值特性与溶剂折射率的关系。对于光谱特性,发现随溶剂的变化,随机激光峰值位置发生明显变化,这主要是由溶剂的吸收位置不同所导致的;在阈值特性方面,观察到阈值随着溶剂折射率的增大而增大。通过引入米氏散射理论,解释了产生这种阈值变化特征的原因是溶剂折射率增大会使随机激光体系的散射强度减小、传输自由程增大。

Rh6G random laser systems are obtained by choosing four solvents （methanol, ethanol, glycol, dimethylsulfoxide） with different refractive indices to disperse Rh6G mixed with 100 nm A1N spherical nanoparticles. It is experimentally investigated that the spectral and threshold characteristics of the Rh6G random laser behaviors. As for the spectra, typical emission evolution spectra are observed. The peak positions vary with the change of solvents, and the reason for the variation is the absorption of the samples. For the threshold feature, the experimental results indicate that the threshold of the random laser depends on the refractive index of the surrounding solvents. The larger the refractive index of scatterers or smaller the refractive index of solvent is, the smaller the threshold will be. The theoretical explanation based on Mie scattering theory for this phenomenon is made. The low threshold random laser is attributed to low refractive index of solvent, which influences the scattering strength, leading to a smaller transport mean free path.