Increasing THz Radiation Power and Monochromaticity Using Optically   Induced Photonic Crystal in Layered Superconductors
  The possibility of enhancing the radiation power and monochromaticity by optically induced photonic crystal in the superconducting cavity is proposed and investigated. In such a structure, by periodically irradiating the stacked Josephson junctions and consequently partially suppression of the superconductivity in the irradiated positions due to depairing, a periodic optical configuration is formed. This leads to photonic band gap opening in the range of the terahertz radiation emitted from the layered superconductor. We show that such a photonic band gap significantly enhances the impedance matching at the boundary of the cavity and the waveguide. Since the weak optical coupling of the outer and inner space of layered superconductor samples is a serious reason of reducing radiated power especially in the experiments, the proposed configuration is capable of extremely enhancement in the emitted power along with attenuation of the undesired harmonics. 
Alireza Kokabi, Hamed Kamrani, Mehdi Fardmanesh
cond-mat.supr-con