Laser optics: Fractal modes in unstable resonators

  title={Laser optics: Fractal modes in unstable resonators},
  author={G{\'a}bor K{\'a}rm{\'a}n and G. S. McDonald and G. H. C. New and J. P. Woerdman},
One of the simplest optical systems, consisting of two mirrors facing each other to form a resonator, turns out to have a surprising property. Stable resonators, in which the paths of the rays are confined between the two mirrors, have a well known mode structure (hermite–gaussian), but the nature of the modes that can occur in unstable reson-ant cavities (from which the rays ultimately escape) are harder to calculate, particularly for real three-dimensional situations. Here we show that these… 
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