Amplitude Characteristics and Frequency Bias in a Zeeman Ring Laser under Three-Frequency Running Wave Excitation

The characteristics of the Zeeman ring laser (ZRL) have been investigated theoretically and experimentally under conditions of two- and three-frequency generation. The influence of the running wave, excited at the third frequency, on the frequency bias and the intensities of counterpropagating waves is examined. A comparison of experimentally measured characteristics with calculations based on vector theory has been conducted. It has been found that when a running wave is excited in a neighbouring longitudinal mode, kinks appear in the dependence of counterpropagating wave intensities on the detuning of the generation frequency from the gain-line center. It is shown that excitation at the third frequency results in a stronger dependence of the frequency bias on the detuning from the gain-line center compared to the two-frequency generation regime. Based on the comparison of theory with experiment, it is demonstrated that among the known values of the isotopic shift between Ne\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}<^>{20}$$\end{document} and Ne\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}<^>{22}$$\end{document} at a wavelength of 0.63 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mu$$\end{document}m reported in the literature, the value \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma=1050$$\end{document} MHz leads to results that do not agree with the experiment, allowing for a refinement of the parameter \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma$$\end{document}.