Localization of a light beam in a narrow inverted zone formed as a result of chemical processes in parallel streams of reagents

It is shown theoretically that injection of an optically dense jet between two parallel planar streams establishes a dielectric gas waveguide which localizes light in a narrow reaction zone. It then becomes possible to use narrow inversion zones (with a thickness of the order of $10^{-2}$ cm) in cw chemical lasers without suffering the diffraction losses of light. This waveguide effect should make it possible to use gas streams at pressures $\gtrsim1$ atm in chemical lasers. A fast chemical reaction, Ba$+$S$_2$Cl$_2\to$S$^*_2$(B)$+$BaCl$_2$, resulting in the emission of visible light is considered by way of example.