Exception of terahertz quantum cascade laser based on new material systems

Terahertz (THz) waves have potential applications in biomedical, astronomy, national defense and other fields. The THz radiation source is a key component for the application of THz technology. The semiconductor-based electrically pumped THz quantum cascade laser (QCL) has attracted the attention of researchers due to its high output power, tunable frequency, and all-solid-state advantages. However, for a long time, the lower operating temperature of the traditional THz QCL based on gallium arsenide (GaAs) material system has restricted its wide application. Through the longitudinal optical (LO) phonons in different materials and their roles in the THz wave emission process, finding a new material system for the preparation of THz QCL is a feasible solution to improve the operating temperature of the device. This article reviews the recent research progress of gallium nitride (GaN) and zinc oxide (ZnO) based THz QCL.