We implemented two different experimental setups to probe directly the nonlinear coupling between modes in microchip lasers. We show that, remarkably, the results can be interpreted by use of Lamb's coupling constant. In an Er, Yb:glass microchip laser, we measured <i>C</i><sub>12</sub> = 0.80 between longitudinal modes and <i>C</i><sub>xy</sub> = 0.95 between orthogonally linearly polarized eigenstates. The high values obtained give some physical insight into the single-frequency operation of such lasers.
© 2000 Optical Society of America
Mehdi Alouini, Fabien Bretenaker, Marc Brunel, Albert Le Floch, Marc Vallet, and Philippe Thony, "Existence of two coupling constants in microchip lasers," Opt. Lett. 25, 896-898 (2000)