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oscillations of the laser pattern as the frequency mismatch of the modes was varied (by varying the astigmatism of the resonator). The experiment shows the predicted hysteresis in the locking and unlocking of the vortex. The experiment also shows that the smallest possible frequency of the oscillations is proportional to the relaxation oscillation frequency.

Fig. 7.10. Locking and unlocking of the “doughnut” in a CO2 laser. The pin position controls the astigmatism of the resonator, and correspondingly the frequency detuning between the Gauss–Hermite modes

References

1.J. Lega, J.V. Moloney and A.C. Newell, Universal description of laser dynamics near threshold, Physica D 83, 478 (1995). 105

2.K. Staliunas and C.O. Weiss, Nonstationary vortex lattices in large-aperture class B lasers, J. Opt. Soc. Am. B 12, 1142 (1995). 108, 110

3.G. Slekys, K. Staliunas, M.F.H. Tarroja and C.O. Weiss, Cooperative frequency locking and tristability in a class-B laser, Appl. Phys. B 59, 11 (1994). 114