Enhancing Goos-Hänchen shift based on magnetic dipole quasi-bound states in the continuum in all-dielectric metasurfaces

Metasurface-mediated bound states in the continuum (BIC) provides a versatile platform for light manipulation at subwavelength dimension with diverging radiative quality factor and extreme optical localization. In this work, we employ magnetic dipole quasi-BIC resonance asymmetric silicon nanobar metasurfaces to realize giant Goos-H\"anchen (GH) shift enhancement by more than three orders of wavelength. sharp contrast GH based on Brewster dip or transmission-type resonance, maximum here is located reflection peak unity reflectance, which can be conveniently detected experiment. By adjusting parameter metasurfaces, $Q$-factor modulated accordingly. More interestingly, it found that exhibits an inverse quadratic dependence parameter. Furthermore, design ultrasensitive environmental refractive index sensor enhanced shift, sensitivity 1.5$\times$10$^{7}$ $\mu$m/RIU. Our work not only reveals essential role BIC engineering basic phenomena, but also suggests way pushing performance limits communication devices, information storage, wavelength division de/multiplexers, sensors.