A new analytical method based on the surface plasmon resonance (SPR) technique is presented, with which SPR curves for both wavelength and angular modulations can be obtained simultaneously via only a single scan of the incident angle. Using this method, the SPR responses of TiO2-coated Cu films are characterized in the wavelength range from 600 nm to 900 nm. For the first time, we determine the effective optical constants and the thicknesses of TiO2-coated Cu films using the SPR curves of wavelength modulation. The sensitivities of prism-based SPR refractive index sensors using TiO2-coated Cu films are investigated theoretically for both wavelength and angular modulations, the results show that in the case of sensitivity with wavelength modulation, TiO2-coated Cu films are not as good as the Au film, however, they are more suitable than the Au film for SPR refractive index sensors with angular modulation because a higher sensitivity can be achieved.
We propose a wideband transverse magnetic-reflected polarizing film composed of Cr and SiO2. Based on the polarization characteristics of reflected light from Cr/SiO2 film, the film can serves as a polarizer to severely attenuate the transverse electric(TE)-polarized light and reflect the transverse magnetic(TM)-polarized light in a wavelength range from 600 to 900 nm. By suitably choosing the film thicknesses, the operation angles of such polarizers can be adjusted over a wide angle range greater than the critical angle of total reflection. Cr/SiO2 film has potential use in surface plasmon resonance(SPR) sensors based on Kretchmann configuration to form integrated structures.
We experimentally investigate the effects of the surface roughness of gold thin films on the properties of surface plasmon resonance. By annealing at different temperatures, film samples with different surface morphologies are obtained. Specifically, due to the diffusion of the gold atoms towards the films3 surface, the surface rootmean-square roughness decreases with the increasing annealing temperature. Then, we measure the surface plasmon resonance of the samples. The results show that the resonance angle of the surface plasmon resonance is sensitive to the root-mean-square roughness, and it gradually decreases by reducing the surface root-mean-square roughness.
