Frequency characteristic of a two-mode ring laser

A theoretical analysis is made of the two-mode regime in a helium-neon ring laser emitting at λ=0.63 μ. Estimates are obtained of the influence exerted by the parameters of the active medium and resonator on the mutual mode locking of the difference frequencies and on the frequency characteristic of the laser. Comparison is made of the frequency characteristics in the one- and two-mode cases.