CAVITY DECAY-RATE AND RELAXATION OSCILLATION FREQUENCY IN UNCONVENTIONAL LASER CAVITIES

Measuring the relaxation oscillation frequency omega(gamma), versus th e normalized pumping rate gamma can provide a useful technique for det ermining either cavity or atomic parameters in many different kinds of lasers. Measurements of relaxation frequency versus pumping rate in a Nd:YAG laser using a gain-guided unstable-cavity design were recently found, however, to yield values of cavity decay rate which were unrea sonably large compared to other estimates of the cavity losses,This di fficulty has been resolved by a closer look at the relaxation oscillat ion dynamics in this type of laser. We find that in nonorthogonal lase r cavities with nonuniform gain distributions the energy decay rate of the cavity oscillation mode usually employed in the relaxation freque ncy formula must be replaced by a different decay rate relevant to osc illation mode perturbations. A numerical simulation including this mor e general effect gives values very close to our experimental results, confirming the validity of this modified analysis.