Magnetic splitting of the nonlinear resonance in the three-level system Ar II

The magnetic splitting of a narrow nonlinear resonance in the threelevel system Arǁn4p$^{2}$D${_5/2}$—4S$^{2}$P$_{3/2}$(λ= 488nm), 4$p^{4}$D$_{5/2}$—4s$^{2}$P_{3/2}$ (λ=514,5 nm)is investigated.Saturation of the transition 4$p^{4}$D$_{5/2}$—4s$^{2}$P$_{3/2}$ was created by single-frequency laser radiation at a wavelangth of 488 nm; probing of the system was performed by a sirigle-frequency laser radiation at a wavelength of 514.5 nm, slightly exceeding the self-exictation threshold; the emission frequency was tuned using a Troitskii selector. It is shown that imposing the magnetic field splits the nonlinear resonance into four components: two weak and two strong. The magnitude of the weak-component splitting is(6.8 ± 0.6) MHz/Oe (theoretical estimates of the Zeeman splitting of the transition 4$p^{2}$D$_{5/2}$—4s$^{2}$P$_{3/2}$ gives a value of 7.1MHz/Oe). The strong-component splitting is an order of magnitude less:experimental value (0.8 ± 0.1) MHz/Oe; calculation 0.82 MHz/Oe.Oscillograms illustrating the splitting of the resonance in a magnetic field are presented.