Modulation of terahertz properties of 3D ceramic photonic crystals via post‐creation non‐metal anion doping treatment.

Ceramic photonic crystals have wide application potentials for THz technology due to their characteristic strong chemical stability and high temperature resistance for demanding environment. However, it is still a challenge to modulate the THz properties of as‐prepared ceramic TPCs via post‐creation treatments to satisfy different application requirements. In this work, the THz properties of rutile TiO2 ceramic 3D‐TPCs were modulated by non‐metal anion doping of either carbon or nitrogen, which was firstly created by the direct‐writing technique with a TiO2 sol‐gel ink followed by the high temperature sintering process at 1200°C. Calcination of the pristine rutile TiO2 ceramic 3D‐TPCs in either CO or NH3 atmosphere successfully doped either C or N dopants into rutile TiO2 ceramic 3D‐TPCs, respectively, which changed their dielectric properties and subsequently induced different THz properties on these ceramic 3D‐TPCs with the same structure. Their THz properties were found to be largely affected by the specific nature of the dopant. Compared with the pristine rutile TiO2 ceramic 3D‐TPC, the bandgap positions of both C‐doped and N‐doped rutile TiO2 ceramic 3D‐TPCs largely shifted toward the higher frequency, while the N‐doped sample demonstrated a much broader bandgap. Thus, non‐metal anion doping could be an effective post‐creation approach to modulate the THz properties of ceramic TPCs. [ABSTRACT FROM AUTHOR]