Low gain laser with an unstable cavity

摘要

A neon 633 nm laser with an unstable cavity was made to lase in the negative unstable region. The characteristic parameters were measured. The loss calculated by using both the geometric approach and the diffraction integral is higher than the gain of the gas mixture, it contradicts the experimental results. If the radial dependence of the gain is taken into account then the calculated loss fits the experimental results satisfactorily.