Optical nonreciprocity in a ring Raman fiber laser

An analysis is made of the conditions of propagation of opposite waves in a ring Raman fiber laser excited by an external periodic signal whose duration is less than the time needed for a round trip in the ring resonator. It is shown that an allowance for nonlinear properties of the fiber gives rise to an optical nonreciprocity in respect of the opposite waves. A calculation is made of the frequency difference between the opposite waves in a ring laser as a function of the laser parameters.