基于辅助电介质层的棱镜表面等离子体共振效应研究

研究了一种基于棱镜基底-辅助电介质层-金膜-待测介质四层结构的表面等离子体共振(surface plasmon resonance,SPR)效应激励模型.采用薄膜光学与波导理论,探索了由辅助电介质层与金膜复合而成共振薄膜对SPR效应的激励机理与调制特性.借助时域有限差分方法,数值模拟得到辅助电介质层属性与共振能量传输特性关系.在此基础上,构建了波长调制型棱镜辅助电介质层结构SPR激励系统.研究结果表明,当待测介质折射率相同时,相较基于棱镜基底-金膜-待测介质三层结构的Kretschmann激励模型,辅助电介质层激励模型共振光谱整体向长波方向偏移且半波宽度出现显著展宽效应.而当待测介质折射率增大时,辅助电介质层型激励模型的共振光谱不仅会向长波方向偏移,而且折射率响应灵敏度比棱镜Kretschmann三层激励模型高出75%.因此该模型能够为诸如高灵敏度检测、新型光学滤波与调制器件设计等领域的研究应用提供理论与实践储备.

Study of prism surface plasmon resonance effect based on dielectric-aided layer

A prism surface plasmon resonance (SPR) incentive model based on the dielectric-aided layer structure is studied. The model consists of four structure layers: prism-dielectric-aided layer-gold-environmental media. According to the thin film optics and waveguide theory, the excited mechanism and modulation characteristic of SPR effect are explored based on resonance composite film composed of dielectric-aided layer and gold film. Numerical simulation is conducted on the relation of layer thickness, film dispersion characteristics and resonance energy transfer by the finite difference time domain method. Thereby, the wavelength modulation prism dielectric-aided layer SPR excitation system is also developed. Results show that with the same refractive index of liquid, the SPR resonance spectrum of dielectric-aided layer incentive model shifts to the longer wavelength region and the resonant halfwave width is wider than the spectrum of common Kretschmann incentive model based on prism-gold-environmental media. With increasing refractive index, the SPR resonance spectrum redshifts, and its sensitity is 75% higher than the common incentive model. The designed model can effectively improve the sensitivity of the prism surface plasmon resonance effect, and in the areas such as high sensitivity detection, new types of optical filter, the modulator and other fields the SPR technology may provide a theoretical and practical basis.