LASER CAVITY WITH A GRADUALLY EXPANDING RADIATION BEAM IN THE ACTIVE MEDIUM

Abstract

Subject and Purpose. Increasing the operational efficiency of laser generators and the amount of their radiated power is an important task in laser development, which can be approached to in a number of alternative ways. The present work has been aimed at increasing the efficiency of energy exchange between the active medium and the laser radiation by way of optimizing the radiated intensity distribution over the entire active volume within the resonant cavity of a novel structure. Methods and Methodology. A model for the process of radiated power amplification in the laser cavity has been considered. Losses within the cavity have been analyzed, as well as possibilities for improving the efficiency of energy transfer from the gain medium to the laser radiation. The importance of optimizing the density of laser radiation in the gain medium is substantiated, and the main problems that might arise clearly identified. The task of increasing the cross-section of the radiation beam being amplified in the active medium has been formulated, and a concept suggested for solving the problem through modification of the telescopic resonator’s optical scheme. Results. A novel configuration has been suggested for the laser resonator, where the radiated beam is expanded in width over two stages of counter propagation. Nonlinear regimes of increasing the beam cross-section in the resonator have been analyzed and recommendations formulated for selecting dimensions of the resonator and geometry of the mirrors, depending on the amount of amplification in the active material. Fragmentation of the output mirror is proposed as a means for feedback optimization, with account of diffraction-caused diver- gence of the radiation. As has been found, field-exciting elements can be placed inside the active medium. Recommendations are developed as for practical application of the scheme proposed in lasers of a variety of frequency ranges. Conclusions. Application of laser resonators of the design considered opens up new possibilities for increasing the efficiency of lasers and their radiated power.