Terahertz quantum cascade lasers

Terahertz (THz) technology deals with electromagnetics, optoelectronics, semiconductor physics, material science, and micro-technology. In applications that cover information science, biology, medicine, astronomy, and environment science the key device is the THz source. We present an overview of THz sources and their potential applications, with emphasis on the basic principle and recent research advances in the development of THz quantum cascade lasers.