Reciprocity between terahertz waves and doped BaTiO₃/SrTiO₃ multilayer films

The carrier absorption of the doped semiconductor materials is evident in terahertz (THz). The reciprocity study is the basis for preparing the key apparatus in the THz communications. Using a pulsed KrF excimer laser ablation (PLD) technique, the Ni-doped BaTiO3/SrTiO3 multilayer film has been prepared. Based on 3.09 THz quantum cascade laser (QCL) with the peak optical power about 10 mW, the transition of THz waves in the Ni-doped BaTiO3/SrTiO3 multilayer films is studied. It is found that the main loss may be due to the nonresonant absorption of Ni particles.