ObjectiveThe investigation of light-matter interaction through quantum control technology stands as a primary research focus in the field of atomic and molecular photon physics. Electromagnetically induced transparency (EIT) is a significant quantum interference phenomenon with crucial applications in optical deceleration, optical bistability, non-inversion lasers, and quantum information. Compared with the transition between atomic hyperfine energy levels, the magnetically induced transition (MIT) between atomic magneton energy levels can be regulated by the external magnetic field. The dark resonance signal with wide range and tunable narrow linewidth is obtained by changing the intensity of the external magnetic field and the frequency detuning of coupling laser, which is of great significance for wide-ranging laser frequency tuning and locking applications.MethodsThe dark resonance effect is investigated through the magnetically induced transitions of ⁸⁵Rb atoms with the external magnetic field based on the Λ-type energy level system of the D2 line. Theoretically, the relationship between the transition probability of different magnetically induced transitions and the magnetic field is calculated. Meanwhile, the dark resonance signal peak frequency with the magnetic field is obtained by calculating the density matrix. In the experiment, the probe laser is scanned near the transition frequency of 5S_1/2 (F_g=3)-5P_3/2 (F_e=1) with σ^- circularly polarization, while the coupling laser is resonant at 5S_1/2 (F_g=2, m_F=0)-5P_3/2 (F_e=1, m_F=-1) transition with σ^- circularly polarization. Finally, the magnetically induced transitions of ⁸⁵Rb atoms 5S_1/2 (F_g=3, m_F=0)-5P_3/2 (F_e=1, m_F=-1) is excited under the magnetic field.Results and DiscussionsThe dark resonance signal peak corresponding to the magnetically induced transitions of ⁸⁵Rb atoms is obtained when the magnetic field is 900 G, which is consistent with theoretical results. The dark resonance signal peak frequency exhibits the linear frequency shift in the negative detuning direction with the magnetic field increasing. The peak position of dark resonance signal shifts ～1.11 GHz when the magnetic field was gradually increased from 900 G to 1200 G in 50 G intervals. The result verifies the tunability of the dark resonance signal peak frequency. The dark resonance signal peak frequency exhibits the linear frequency shift in the positive detuning direction as frequency detuning of the coupling laser increasing. When the frequency detuning of the coupling laser gradually increases from 0 to 200 MHz in 40 MHz intervals, the peak position of dark resonance signal shifts ～0.25 GHz. These experimental results agree with the theoretical fitting results.ConclusionsThe experimental results indicate that the dark resonance signal peak position with controlled tuning is achieved by adjusting the external magnetic field and positive frequency detuning of the coupling laser. This work offers potential value for wide-range tunable laser frequency locking far from alkali metal atomic resonance transition positions.