Studies On Terahertz Laser Optically Pumped By A TEA CO₂ Laser And Its Application

various areas. The application is less about TeraHertz radiation mainly due to the lack of effective source and measuring means of terahertz radiation. With the continuous development of TeraHertz technology in recent years, measurement and application of TeraHertz radiation is going to be the hot research topic.In this thesis, characteristics of terahertz laser beam such as the wavelength, the energy, the waveform, the polarization state and the beam mode are measured based on the research of pulsed THz laser pumped by tunable TEA CO2 laser, the technology of THz wavelength measurement based on Fabry-Perot interferometer is introduced detailedly.As the typical application of the high-energy terahertz radiation, the monopulse transmission imaging detected by an array detector is studied. Details are as follows,(1) When 9R (16) transition acts as the pump line, the energy of 55.5mJ and the pulse width of 2μs is measured. When 9R (16) and 10P (32) transition acts as the pump line, the polarization states we measured are parallel and perpendicular, the focused spot diameters are 8.3mm and 9.4mm,the far-field divergence angles we caculated are 83mrad and 52.2mrad which are 11.2times and 11.9times diffraction limit. The NH3 is working gas in the cavity.(2)The tunable Fabry-Perot interferometer is composed by two pieces of Wire-grid Polarizers. The measured wavelengths of two THz radiations whose theoretical wavelengths are 90±1μm and 151.5±0.5μm are 90.69±0.22μm and151.79±0.37μm, the error is less than 1%.(3)The experimental facility of THz transmission imaging is designed. It is detected on small size metal objects without and with package clearly. It proves the detecting effect is favorable on THz imaging for the metal objects.