THz emission from intrinsic josephson junctions in high-Tc superconductors for imaging applications

In 2007 [1], we have succeeded in observing strong, coherent, and continuous THz emission from a mesa of Bi₂Sr₂CaCu₂O_8+s single crystal with a rectangular dimension of a few hundred micrometers in length, several tens of micrometers in width, and a few micrometers in thickness. Since then, great progress has been made both in understanding the fundamental mechanism of the radiation [2-6] and in practical applications [7-9]. Here, we show the present status of the THz radiation from high-T_c superconductor Bi₂Sr₂CaCu₂O_8+δ mesa structures in comparison with the other fast developing solid state THz sources such as resonant tunnelling diodes (RTD), uni-travelling carrier photodiodes (UTCP) and quantum cascade lasers (QCL), etc.