Elimination of Chaos in Multimode, Intracavity-Doubled Lasers in the Presence of Spatial Hole-Burning

Abstract

In this paper possibilities of a stabilization of large amplitude fluctuations in an intracavity-doubled solid-state laser are studied. The modification of the cross-saturation coefficient by the effect of spatial hole-burning is taken into account. The stabilization of the laser radiation by an increase of the number of modes, as proposed in [James et al., 1990b, Magni et al., 1993, is analyzed. It is found that when the crosssaturation coefficient is modulated by the spatial hole-burning the stabilization is not always possible. We propose a new way of obtaining a stable steady-state configuration based on an increase of the strength of nonlinearity, which leads to a strong cancellation of modes, so that during the evolution all of the modes, but a single one, are canceled.Such a steady-state solution is found to be stable with respect to small perturbations.

Antiphase state in passivelyQ-switchedYb:YAGmicrochip multimode lasers with a saturable absorberGaAs

“…This shows that the two modes oscillate in opposite phase-the maxima of one mode coincide with the minima of the other. The antiphase motion created from the cross-saturation mechanism due to spatial hole burning couples the modes via population gratings the same as reported by other researchers [2][3][4][5][6][7][8][9][10]. The most interesting thing is that as soon as the pump power is increased up to the three-mode regime, in which the third lasing mode begins to oscillate, the dynamics changes, and intensity pulsations occur of the first mode with the highest gain characterized by two pulses as a group, which are different from those occurring in two modes, as shown in Fig.…”

“…In that state, all oscillators are in the same periodic state, but each oscillator is shifted by 1 / N of a period from its neighbor. Similar states were identified first in the output of a multimode laser with an intracavity doubling crystal [2][3][4][5][6][7], and subsequently with gain or loss modulation [8][9][10]. Other work on this topic has extended the definition of antiphase dynamics even further, to the transient approach to stable steady states.…”