Abstract

A Ne (6328-Å) laser with an unstable cavity has been made. It lases over a wide range in the unstable region. The computation shows that the eigenwaves exist in the asymmetric confocal cavities which have an aperture inside at the confocal plane. The distribution of E is only the function of the magnification β and Fresnel number N. The loss δ depends on both β and N; for the case of N = 0.80 and β = −1.02, the loss δ = 0.9% which is acceptable with a Ne laser. The high-order transverse modes also exist. For a general negative unstable cavity with an inside aperture at one of the conjugate image points, there is an equivalent asymmetric cavity having the same β and Was the general case. These two cavities have the same E distribution and loss (E up to a phase factor).

© 1987 Optical Society of America