UNIVERSAL DYNAMICAL PROPERTIES OF 3-MODE FABRY-PEROT LASERS

We present an asymptotic study of a three-mode Fabry-Perot laser with arbitrary relative modal gains in the rate equation limit. Dynamical m odes are defined as the eigenvectors of the stability or Jacobian matr ix. The associated eigenvalues are the decay rates and the relaxation oscillation frequencies. We show that if the modal gains are not equal , the ratio of the relaxation oscillation frequencies may display rati onal ratios which will lead to resonances. We classify the various sta tes of the modal field intensities as in-phase, partial and perfect an tiphase and find universal relations between the peak heights in the p ower spectra of the total and of the modal intensities at each of the relaxation oscillation frequencies. Our theoretical results are confir med by numerical computation using the full rate equations. Experiment al results obtained for the noise spectrum of an LNP microchip laser f ully support our theoretical results. We also conjecture some properti es of lasers operating in an arbitrary N-mode regime.