Opening of Hybrid Bandgaps in Two-Dimensional Photonic Crystals of Pb(Mg$_{1/3}$Nb$_{1/3}$ )O$_{3}$–PbTiO $_{3}$ Having Very Low Refractive Index Contrast

The effect of anisotropy on two-dimensional photonic crystals of hexagonally arranged Pb(Mg
_1/3
Nb
_1/3
)O
₃
-PbTiO
₃
(PMNT) rods in air background was analyzed using a finite-difference time-domain method. The refractive index contrast between PMNT (n = 2.47) and air is low compared to conventional semiconductor-air photonic crystals. Yet, hybrid (polarization-independent) photonic bandgaps were achieved for anisotropic PMNT rods by adjusting the structural parameters and the anisotropy. The maximum bandwidth found was 20 nm. It was possible to engineer the center wavelength of this bandgap to 980, 1300, and 1550 nm, for potential applications as switches, electrooptic filters, and modulators in this region.