Increase in the amplitude of a saturated absorption resonance in an active interferometer

The behaviour of the amplitude of a saturated absorption resonance observed in laser radiation propagated through an active interferometer with nonlinear amplifying and absorbing media is studied experimentally for the first time. Upon variation of the gain in the amplifying medium and preserving a constant saturating field in the interferometer, a nonlinear increase in the amplitude of the saturated absorption resonance was observed. In this case, an increase in the detected signal exceeded an increase in the noise, i.e., the signal-to-noise ratio also increased.