Pioneering studies and cutting-edge approaches in the terahertz-waves region

Progress in far-infrared and terahertz technology is reviewed. There are three ways of approach to this frontier region; optic, electronic or quantum electronic approach. This paper describes optic, i.e. grating and Fourier-transform spectroscopy, and quantum electronic, i.e.far infrared lasers and terahertz time-domain spectroscopy / imaging (THz-TDS). Applications by use of each method are shown.