Control of intrapulse frequency chirping in long-pulse CO(2) lasers employing perturbation-insensitive optical cavities.

We present the results of intrapulse frequency chirping measurements that were carried out on a TEA CO(2) laser equipped with various conventional and unconventional frequency-selective optical cavities. We experimentally demonstrate that there is a close relationship between the causes and the extent of intrapulse frequency chirping on the one hand and the type of optical configuration that is used for controlling the laser mode behavior on the other. In particular, it is shown that intrapulse chirping of the emitted frequency can be significantly reduced by employing laser cavities terminating in high-finesse reflective multipass interferometers for single-mode selection. In fact, this type of cavity can be designed in such a way to minimize the effects on the emitted frequency of perturbations affecting the cavity optical length.