Fig. 1. Experiment setup of weakening frequency difference lock-in phenomenon in a Y-shaped cavity dual-frequency laser. PZT1, PZT2: piezoelectric transducer; P: polarization plate; D: photoelectric detector; SA: spectrum analyzer; HC: Helmholtz coil pair; HCPS: power supply for Helmholtz coil pair; PZTPS: power supply for PZT.

Fig. 2. Configuration of the cube coil pair.

Fig. 3. Magnetic field intensity distribution along the y axis in the plane zoy, for a different current I.

Fig. 4. Distribution of longitudinal modes along the frequency axis. Dashed lines represent P-light; solid lines represent S-light; arrows indicate the directions along which the longitudinal modes move while the voltage applied to PZT2 is increasing.

Fig. 5. Minimal frequency difference varying with different magnetic field intensity. Δ: experimental data.

Fig. 6. Frequency differences tuning with the voltage applied on PZT2 when the magnetic field intensity is about 9 mT.