The THz region is defined as the frequency range from 0.1 to 10 THz (corresponding to the wavelength from 30 to 3000 μm or photon energy from 0.41 to 41 meV). The THz frequency regime is located between the mid-infrared and submillimeter wave band. Because of the outstanding properties in both light and wave aspects, the THz technology is of great importance in areas such as properties investigations of semiconductor materials and high temperature superconducting materials, tomography, unmarked gene examination, cellular imaging, chemical and biological examination, broadband communications, security imaging, and non-destructive detection. 

After years of development, SIMIT established a complete process and characterization platform for terahertz solid-state device, and made a number of important progress on terahertz radiation source, detector and THz applications, and exerted an important influence in the terahertz research field. In the field of terahertz photonics, theoretical and experimental research of terahertz radiation sources and detectors has been carried out systematically in SIMIT. The impact ionization model of terahertz radiation has been developed, and the variation rule of terahertz absorption coefficient with the radiation intensity has been explained. The first domestic research and development of high-performance terahertz quantum cascade laser and terahertz quantum well detectors were realized and used in the fields of terahertz communications and imaging. The successful development of terahertz quantum well detectors – light emitting diode devices overcome the challenges of terahertz detector array and demonstrated the terahertz focal plane pixelless imaging technology. Based on the high performance terahertz QCLs, we successfully achieved terahertz frequency comb operation in QCLs. In the continuous wave mode, the terahertz QCL frequency comb can span over 330 GHz (8% of the central frequency) that is the record for the QCLs with a bound-to-continuum active region design. In the field of terahertz electronics, SIMIT took the lead in developing Ka-band miniaturized anti-collision radar in China, and carried out the research and development of GaAs millimeter-wave monolithic integrated circuits since 2003. At present, the K-band Ka-band, V-band, E-band and W-band series of the MMIC chip sets with independent intellectual property rights, have been formed and applied to the millimeter-wave communication and detection system. SIMIT has prepared the first 60GHz communication chip sets based on vector modulation technology in China, and the MMIC chip applied to 5G communication has been successfully supplied to Huawei Technologies Co., Ltd. The Ka-band V-band and W-band miniature radar detector was successfully installed by SIMIT. Furthermore, SIMIT has manufactured SimImage, a human security inspection imaging equipment with completely independent intellectual property rights, won the silver award at the 2016 China International Industry Fair and succeeded in transforming the achievements.