Spectral structure of pulse superluminescence lines of gases

An experimental investigation was made of the spectral structure of several superluminescence lines of Ne, Pb, and Tl excited by electric discharge pulses. These superluminescence lines were found to consist of several components. The widths of the components were governed by the reciprocal of the superluminescence pulse duration. A reduction in this duration, observed when the gas pressure was increased, resulted in characteristic changes in the spectra. The observed structure was attributed to a fluctuation (random) spectrum which became regular in the process of propagation of a signal across a nonlinearly amplifying medium.