Abstract-The Special Polarization Characteristic Features of a Three Dimensional Terahertz Photonic Crystal not apparently apply to physical and optical basic rules

Chikara Sakurai

https://arxiv.org/abs/1801.06741

A Si inverse diamond structure whose lattice point shape was vacant regular octahedrons had a complete photonic band gap at around 0.4 THz and X point's photonic band gap (0.36−0.44 THz) by plane wave expansion method. It is said that three-dimensional photonic crystals have no polarization anisotropy in photonic band gap (stop gap, stop band) of high symmetry points in normal incidence. Experimental results, however, confirmed that the polarization orientation of a reflected light was different from that of an incident light. The direction of the incident light was [001] (Γ-X direction). The polarization orientation of an electrical field was parallel to the surface (001) of the photonic crystal and was set in the orientation defined as θ degree. θ was 0∘ to 90∘ per 15∘. A sample was rotated in plane (001) instead of the incident light, relatively. The polarization orientation of the reflected light was parallel to that of the incident light for θ = 0∘ and 90∘, in contrast, the former was perpendicular to the latter for θ = 45∘ in the vicinity of 0.42 THz. For an intermediate θ, the former was an intermediate orientation. As far as the photonic crystal in this work is concerned, these phenomena don't apparently apply to physical and optical basic rules.