Broadband spectral measurement of Goos-Hänchen shifts by hyperspectral SPR imaging

Goos-Hänchen (GH) shift is a combination of displacement and deflection of the reflected beam with respect to the geometric optical reflection path, which is caused by non-ideal plane wave reflection. GH shift is wavelength dependent, especially in photonic and plasmonic resonance structures. However, there are few studies on the dispersion properties of GH shift. In this paper, we proposed a broadband spectral measurement method for GH shifts, which is implemented using a hyperspectral surface plasmon resonance imaging (HSPRi) sensor constructed in our laboratory. The HSPRi sensor has a wide wavelength range of 400 nm to 1000 nm and can provide up to 1456 grayscale images of different wavelengths. By calculating the centroid position of each grayscale image, the SPR-enhanced GH shifts as a function of wavelength are obtained for the sample under study. The simulation and experimental results of the GH shift on the surface of the 50-nm gold film are almost identical, verifying the reliability and accuracy of the proposed method for measuring GH shift dispersion.