Operation of an externally locked ring laser

A theoretical analysis is given of the influence of a resonance signal on the stability of a single-frequency traveling-wave laser. A one-dimensional model of a ring laser is used. It is assumed that the active medium of this laser has a homogeneously broadened luminescence line. The losses in the laser resonator are concentrated. It is also assumed that the external signal frequency coincides with the emission frequency and they are both equal to the central frequency of the luminescence line. It is shown that the critical value of the excess of the pump power over the threshold at which the single-frequency emission becomes unstable increases with rising intensity of the external signal but always remains finite.