Starting mechanism in coupled-cavity modelocked laser systems

The starting mechanism in coupled-cavity, additive pulse mode-locked (APM) lasers is discussed theoretically and demonstrated experimentally. Short- and strong-mode beating noise bursts that can overcome dynamic gain saturation in large emission cross-section gain media result from the etalon effect of the coupled cavity that forces lasing at two separate frequencies. We have measured terahertz-mode beating fluctuations, that are in quantitative agreement with our theory, in a coupled-cavity NaCl color-center laser. A detailed comparison between theory and experiments is presented, and implications regarding other laser systems are discussed.