Amplitude and frequency characteristics of ring gas lasers

An experimental investigation was made of the amplitude and frequency characteristics of ring gas lasers. The first determinations were made of the dependences, on the resonator tuning Δ, of the additional frequency shift of beats (averaged over the total phase ψ of the coupling coefficients) and of the phase shift φ₀ between the variations (due to the change in ψ) of the beat frequency and the wave intensities. A comprehensive investigation was made of the dependences of the beat frequency Ω_b and of the intensities of the opposite waves on the ring resonator tuning and on the total phase ψ of the coupling coefficients. These dependences made it possible to compare several modifications of the theory of ring gas lasers. Far from the frequency locking region the dependence Ω_b(Δ) was found to be mainly due to the difference between the resonator losses experienced by the two opposite waves. When the pump intensity was increased, the deviation of the beat frequency Ω_b(Δ) increased. The experimental results were compared with the theory of ring gas lasers.