Amplification of a weak signal on reflection from an inverted medium

An experimental investigation was made of the influence of the reflection conditions and of the characteristics of the incident radiation on the amplification of light in the course of its reflection by an excited dye solution. A strong dependence of the reflection coefficient on the angle of incidence was observed and its maximum occurred near the critical angle of total reflection. The amplitude and width of the reflection peak depended on the parameters of the ambient media, as well as on the spectral composition and energy of the incident radiation.