Self-Mode Locking in Inhomogeneously-Broadened CW Lasers.
MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL ENGINEERING
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An experimental and theoretical discussion of self-mode locking in multimode CW gas lasers is presented. The average saturated gain profile is assumed to be nearly flat in the frequency range of the oscillating modes because the homogeneous pressure-broadened linewidth is larger than the intermode frequency spacing. For He-Ne and He-Cd lasers the gain fluctuations which occur as the pulses propagate through the active medium are believed to be small since the pulse velocity has been found to be approximately the same as the group velocity associated with the average dispersion. Estimates of the recovery time for the inversion density in a He-Ne laser indicate that the gain variations are a few percent of the average gain. An experimental technique for measuring the mode phases was developed, and measurements were made on a self-locked He-Ne laser with about seven modes. The results show that the modes are not in phase, and that, for the particular laser used, one mode toward the high-frequency end of the spectrum is lagging the others in phase by about 40 degrees. Author
- Lasers and Masers