Energy gap 2 Photonic band gap A-plane 1 Bound state in the continuum 1 Bound-states 1 Crystalline substrates 1 Dielectric layer 1 Dielectric medium 1 Dielectric permittivities 1 Dielectric permittivity 1 Differential equations 1 Diffraction 1 Elastic waves 1 Electromagnetic plane wave 1 Enhanced light absorptions 1 Germaniums (Ge) 1 Gradient refractive index 1 Light absorption 1 Metasurface 1 One dimensional 1 One-dimensional 1 Optical- 1 Permittivity 1 Photonic bandgap (PBG) 1 Photonic crystals 1 Plane wave 1 Plasmon-polaritons 1 Reflection and transmission coefficients 1 Refractive index 1 Systems support 1