Transverse mode formation in microlasers by combined gain- and index-guiding

The formation of transverse modes in end-pumped microlasers with combined index- and gain-guiding is investigated theoretically, We study the case of a planoconcave cavity pumped by means of a Gaussian optical field in the frame of the effective index method and the mean-field limit. We find crossings of the modal gains as the cavity losses are varied. Ring patterns are observed in both the near- and far-field profiles in qualitative agreement with the experiments. We study the bad-cavity region and observe one compact trapped gain-guided mode with large modal gain, and many other deformed index-guided modes with much less gain.