TOTAL INTENSITY MODULATION AND MODE HOPPING IN A COUPLED-CAVITY LASER AS A RESULT OF EXTERNAL-CAVITY LENGTH VARIATIONS

Subwavelength variation in the length of an external cavity strongly coupled to a very short (100 mu m) dye laser results in large changes in the total intensity and frequency hopping of the lasing modes. These measurements are in agreement with a multimode theory of coupled-cavity laser dynamics. The modulation in the total intensity is due to the frequency-dependent gain associated with the coupled-cavity mode structure, while the mode hopping characteristics can be attributed to frequency-dependent losses caused by very weak (similar to 10(-3)) reflections or diffuse scattering from the glass surfaces in the system.