Nv. Kupryaev et al., GENERATION OF SINGLE-MODE RADIATION IN A WIDE-APERTURE UNSTABLE CAVITY WITH A SEMITRANSPARENT EXIT MIRROR AND INTRACAVITY ASTIGMATISM, Kvantovaa elektronika, 23(4), 1996, pp. 356-358
An experimental investigation was made of a laser with an unstable cav
ity and coupling out of the radiation through a homogeneous semitransp
arent mirror. The feasibility and conditions of attaining single-mode
emission were studied for Fresnel numbers of the order of 10 in the pr
esence of considerable intracavity astigmatism. The condition for sing
le-mode emission from such a laser was an instability of the cavity in
at least one of the symmetry planes imposed by astigmatism.