Optical characteristics of surface plasmon resonance based on Au photonic crystal structures

摘要

We proposed the photonic crystal coupled surface plasmon resonance sensors using gold nano-structure to enhance the sensitivity of an SPR sensor. The proposed configuration with the photonic crystal structure is Au(Photonic crystal)/Au/Ag/Cr/Glass. The 20 nm silver film and the 20 nm gold film are layered on the glass substrate. Then, the dot-like gold photonic crystal structures with a period pitch are patterned on the Au/Ag/Cr/Glass structure. The reflectance and the optical-mode propagations as a function of incident angle are calculated using the three-dimensional finite-difference time-domain method. Under this resonance condition, the incident light is highly absorbed and loses a fair amount of its energy, which results in a dip in the intensity profile of the reflected light. The optimum resonance angle of 44.5 degrees is obtained in the 75-nm-radius Au photonics crystal structure with a period of 300 nm