Enhanced the tunable omnidirectional photonic band gaps in the two-dimensional plasma photonic crystals

In this paper, the features of omnidirectional band gap (OBG) in the two-dimensional (2D) plasma photonic crystals (PPCs) with triangular lattices are theoretically studied in detail by the modified plane wave expansion method as the off-plane incidence wave vector is considered, which are composed of the non-magnetized plasma cylinders inserted into the homogeneous and isotropic dielectric background. The simulated results demonstrate that a flatband region and the OBG can be obtained in the proposed PPCs. The influences of the radius of inserted cylinder and plasma frequency on the OBG are investigated. The calculated results illustrate that not only the tunable OBG can be obtained but also the achieved OBG also can be enlarged by optimizing those parameters. To enhance the OBGs, two novel configurations of PPCs are present. The computed results reveal that the proposed two configurations have the advantages of obtaining the larger OBGs compared to the conventional 2D PPCs since the symmetry of 2D PPCs is broken, and the OBGs also can be manipulated obviously by changing the geometric parameters of such two PCs structures. Introducing the anisotropic dielectric (uniaxial material) into the proposed 2D PPCs to enlarge the OBGs also is studied. The effects of ordinary-refractive and extraordinary-refractive indices of uniaxial material on the properties of OBGs also are investigated in theory, respectively. The computed results show that the OBGs can be enlarged by introducing the uniaxial material, and the OBGs also can be tuned by changing the parameters of uniaxial material.