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

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