Influence of non-local radiation transport on the gain of a He-Ne ring laser

A global modeling of a He-Ne ring laser gyro (RLG) has been developed. The physical model of the positive column of the DC discharge includes a fluid description of the plasma, a collisional radiative model (1D-CRM) for the dynamics of excited atomic states and a Maxwell-Bloch calculation of laser amplification. In the present paper we use this global modeling to analyze the influence of the radial transport of excited states, through diffusion and radiative transfer, on the radial profile of the laser gain. Concerning radiative transfer, a full matrix transfer has been determined using a Monte-Carlo calculation and introduced in the 1D-CRM. Using this code, we have analyzed the influence of the boundary condition for the diffusion equation at the capillary walls on the metastable atom densities and on the laser gain.