Rotational transition competition in a single-mode CO2laser

In the present work we have investigated the mechanism of rotational transition competition of a single-mode laser by studying the effect of small variations of the out-coupling loss factor. For this purpose we used on the out-coupling side one extra mirror with a reflectivity of only 1 percent. In this way the instability problem could be followed with a controllable out-coupling device having a variable reflectivity between 73.6 and 81.5 percent and a corresponding variation in out-coupling loss factor. Due to the nonzero rotational relaxation time we find a narrow range of the gain-to-loss ratio of respective transitions to have nonsingle oscillations. We have observed single as well as multioscillating transitions as a function of the loss factor.