Abstract
Possibilities and advantages of the electro-optical sampling (EDS) technique for the investigation of excitation of THz-range 2D plasma waves in FET/HEMT channels are considered both experimentally and theoretically. It is experimentally demonstrated that the EOS technique allows one to identify an excitation of 2D plasma waves in the HEMT channel under a given working point determined by external embedding circuits. Theoretical simulations show that the development of the instability of 2D plasma waves can be easily identified in the framework of the EOS technique.