Ab initio multimode linewidth theory for arbitrary inhomogeneous laser cavities

We present a multimode laser-linewidth theory for arbitrary cavity structures and geometries that contains nearly all previously known effects and also finds new nonlinear and multimode corrections, e.g., a correction to the α factor due to openness of the cavity and a multimode Schawlow-Townes rela...

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Bibliographic Details
Main Authors: Pick, A., Cerjan, Alexander, Liu, D., Rodriguez, A. W., Stone, A. D., Chong, Yi Dong, Johnson, S. G.
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2015
Online Access:https://hdl.handle.net/10356/103354
http://hdl.handle.net/10220/38745
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Institution: Nanyang Technological University
Language: English
Description
Summary:We present a multimode laser-linewidth theory for arbitrary cavity structures and geometries that contains nearly all previously known effects and also finds new nonlinear and multimode corrections, e.g., a correction to the α factor due to openness of the cavity and a multimode Schawlow-Townes relation (each linewidth is proportional to a sum of inverse powers of all lasing modes). Our theory produces a quantitatively accurate formula for the linewidth, with no free parameters, including the full spatial degrees of freedom of the system. Starting with the Maxwell-Bloch equations, we handle quantum and thermal noise by introducing random currents whose correlations are given by the fluctuation-dissipation theorem. We derive coupled-mode equations for the lasing-mode amplitudes and obtain a formula for the linewidths in terms of simple integrals over the steady-state lasing modes.