Enhanced spatial shifts of reflected beam on natural hyperbolic materials by polariton conversions

• Generation conditions of ghost evanescent polaritons are strictly proved. • Enhanced spatial shift with high reflection resulting from polariton conversion. • Provide a new perspective to realize the direct observation in applications. We conducted comprehensive analyses for the sudden enhancement of Goos-Hänchen (GH) or Imbert-Fedorov (IF) shift with a high reflectivity, where a beam is incident on the surface of a natural hyperbolic material. The research reveals that the GH shift is evidently enhanced at the conversion points among evanescent and bulk polaritons, which is the main conclusion. We further found both the GH and IF shifts are remarkable at the conversion point between bulk and ghost evanescent polaritons. The simulations with Comsol Multiphysics software further confirm that these points correspond to specific frequencies f / f t = 1.09 and 2.155 ( f t = 760 c m − 1 ) . In addition, the impacts of the incident angle, orientation angle of the optical axis, and crystal damping on the spatial shifts are examined. A new perspective is proposed for improving the GH and IF shifts with high reflection in optical device development.