Ring gas laser with a strong coupling between traveling waves

A theoretical analysis is made of the operation of a single-mode ring gas laser with a strong coupling between traveling waves as a result of back reflections. It is shown that when the coupling coefficient exceeds a certain critical value, a spontaneous oscillatory energy transfer from one wave to the other and back again is observed at the centers of the gain and absorption profiles. Under certain conditions this may give rise to extremely narrow power resonances characterized by a 100% contrast.