Brief Communications

Nature 402, 138 (11 November 1999) | doi:10.1038/45960

Laser optics: Fractal modes in unstable resonators

G. P. Karman2,1, G. S. McDonald1,1, G. H. C. New1 & J. P. Woerdman1

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 situations1. Here we show that these peculiar eigenmodes of unstable resonators are fractals, a finding that may lead to a better understanding of phenomena such as chaotic scattering and pattern formation. Our discovery may have practical application to lasers based on unstable resonators1.

  1. Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
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  2. Blackett Laboratory, Imperial College, London SW7 2BZ, UK
  3. Present address: Philips Research Laboratories, Prof. Holstlaan 4, 5656 AA Eindhoven, The Netherlands