Abstract Theory of the coherent-mode decomposition of laser beams is proposed. The new model for the flat-topped beams proposed by Li recently is taken as an example. The analytical expressions for the $M^2$-factor and mode coherence coefficients of flat-topped beams have been derived in the rectangular coordinate system, by means of which the mode correlation, mode structure, and coherent-mode decomposition of flat-topped beams can be analysed.
Received: 22 April 2003
Revised: 02 January 2003
Accepted manuscript online:
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