Two-level gas laser with transverse diode pumping

Abstract

We theoretically study a new method for generating laser radiation by a two-level system without population inversion in the ‘red’ wing of its spectral line under resonant absorption of broadband radiation from pump laser diodes. A two-level system simulates the atoms of an active gas in an atmosphere of a high-pressure buffer gas. The effect results from the fact that in the ‘red’ wing of the spectral line, the probability of stimulated emission exceeds the probability of absorption if the homogeneous broadening due to the interaction of particles with the buffer gas significantly exceeds the natural one (at high pressures of the buffer gas). Analytical formulae are obtained that describe the operation of a two-level gas laser with transverse diode pumping. It is found that the longer the active medium, the higher the buffer gas pressure and pump radiation intensity, and the smaller the width of the pump radiation spectrum, the greater the efficiency of conversion of pump radiation into laser radiation. In a sufficiently long active medium (the length of the medium is 50 times its width), the conversion efficiency can reach 44 % at a buffer gas pressure of 5 atm, a pump diode radiation intensity of 3 kW cm−2, and a half-width of its spectrum of 1 cm−1. A two-level gas laser with transverse diode pumping is capable of generating continuous optical radiation with a very high (up to 100 kW) power. The frequency of laser radiation can be tuned by several tens of cm−1.