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Large Petermann factor in chaotic cavities with many scattering channels.

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<mark>Journal publication date</mark>2000
<mark>Journal</mark>EPL
Volume49
Pages (from-to)48
Publication StatusPublished
<mark>Original language</mark>English

Abstract

The quantum-limited linewidth of a laser cavity is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. The average Petermann factor <K> in an ensemble of cavities with chaotic scattering and broken time-reversal symmetry is calculated non-perturbatively using random-matrix theory and the supersymmetry technique, as a function of the decay rate Gamma of the lasing mode and the number of scattering channels N. We find for N>>1 that for typical values of Gamma the average Petermann factor <K> propto N >> 1 is parametrically larger than unity.