Resonant cavitylike modes in dielectric photonic crystals made of collections of subwavelength cylinders

We investigate resonant cavitylike modes in dielectric photonic crystals made of collections of subwavelength cylinders with high permittivity. A large number of collective modes appear for TE polarization (where magnetic fields are oriented along the cylinder axis), which possess similar features of resonant cavity modes that occur in polaritonic structures. These modes are dispersionless in nature and intensively gathered around an asymptotic frequency that depends on the subwavelength cylinders. The typical resonant cavitylike modes are illustrated with the magnetic field distributions at the resonant frequencies. In particular, the field pattern in the building block shows a close resemblance to TEnm mode of an isolated waveguide. The respective cutoff frequency at large oscillation orders serves as the asymptotic frequency of resonant cavitylike modes.