Nonlinear spectroscopy within a Doppler profile based on "competitive" resonances

An analysis is made of the width and resolution of "competitive" power resonances in a ring gas laser with a nonlinearly absorbing cell in the resonator. It is shown that in the case of the Lorentzian profile of an inverted Lamb dip in a nonlinearly absorbing cell the resolution of competitive resonances is equal to the homogeneous linewidth in spite of the fact that the width of competitive resonances is much smaller than the homogeneous width (Lamb dip width). An analysis is made of the narrowing of the tip of the Lamb dip in the case of long-lived molecular levels and particularly of the field broadening of the narrowed tip. It is found that the resolution of competitive resonances in the case of a narrowed tip of a Lamb dip in a low-pressure gas cell may be much higher than the resolution governed by the time needed to cross a light beam by molecules with an average thermal velocity.