Gas-discharge lasers of the terahertz range

The terahertz (THz) frequency range now attracts much attention of researchers and consumers in connection with many possibilities of using it for solving a number of practical problems in science, technology and medicine. Therefore, the development of new sources of radiation and the improvement of the existing ones are actual. The results of experimental and theoretical studies of gas-discharge THz-lasers, and numerous studies of the features of their work have been summarized in the paper. A number of new developments aimed at increasing the efficiency and expanding the functionality of gas-discharge terahertz lasers have been presented. New methods of pumping gas-discharge lasers, which were developed, have been presented. We have proposed new technical solutions which allow increasing the power and efficiency of the laser by optimizing the synthesis of the active substance and eliminating the negative impact of synthesis by-products. New methods for modeling the shape of laser pulses in lasers pumped with pulsed current and alternating low-frequency current have been presented. New types of laser resonators and new varieties of mirrors have been proposed and created and they have been presented in this work. Laser resonators with mirrors that do not require accurate alignment have been developed. Partially transparent mirrors, in the form of flat periodic structures that combine the functions of concave mirrors and focusing lenses, have been proposed. These mirrors can reduce the diffraction loss of laser radiation. Resonators with new principles of smooth regulation of radiation output from them, have been presented. Multifrequency lasers have been developed. Systems for the smooth adjustment of the frequency of electromagnetic laser radiation, in which adjustment is carried out without the use of frequency measuring equipment, have been designed for these lasers. All these new developments, presented here, have made it possible to improve the parameters of terahertz lasers and to expand their field of application. Some applications of THz lasers, in particular medical applications and in the field of measurement have been presented. New ways of measuring the refractive indices of various substances and materials in the THz range, using the developed lasers, have also been presented in this work.