Spontaneous pulsations in laser oscillators: Effects of spatial field distributions; self-mode-locking dynamics; pulsations in 3.39 micrometer helium-neon standing-wave lasers

Some lasers with steady-state excitation exhibit undamped pulsation outputs. In this study, rigorous models for such pulsation dynamics have been developed. These models can be used to investigate the effects of non-ideal spatial distributions of the electric field on the instability behavior.; General models for both homogeneously and inhomogeneously broadened, uni-directional ring laser oscillators with nonuniform plane-wave electric field distributions are derived. Linear stability analysis is performed on the steady-state solutions when they are subjected to small perturbations. The results show that the inclusion of a nonuniform plane-wave electric field distribution tends to raise the perturbation instability threshold above that of laser models with a uniform plane-wave electric field.; A laser model that describes spontaneous self-mode-locking dynamics in long-cavity mixed-broadened unidirectional ring laser oscillators is developed. The general model, for lasers with different gain media and cavity lengths, allows for investigations of pulsation dynamics in lasers with discrete losses, where the arbitrary coupling loss at the output mirror and other losses in the system are considered separately. When applied to a specific laser, i.e., a xenon laser, for which published experimental data at various cavity lengths and pump rates is available, the results of the numerical calculations show rich pulsation behavior similar to those observed experimentally.; Spontaneous pulsations have been observed in single-mode standing-wave 3.39μm He-Ne laser oscillators. A model for this effect is reported, and the results include direct comparisons between theoretically calculated results and published data for this type of laser. Good agreement is obtained for both the threshold for instability and the corresponding peak pulsation frequency. Other previously reported features, such as the complex structures of the homodyne and heterodyne spectra as the threshold parameter or the cavity detuning is varied, the narrow range of pulsations around the line center, anomalous mode-pulling behavior, and the varying depth and the width of the Lamb dip are all in agreement with the theoretical results.