Fig. 1. Illustration of the RFOG system and the frequency components in the CW and CCW directions. C1 and C2: couplers.

Fig. 2. Spectrum after the phase is modulated, and the carrier component ω0 is suppressed.

Fig. 3. Illustration of carrier suppression by locking the sideband to the cavity resonance.

Fig. 4. (Color online) Whole scheme when sideband locking and different modulation frequencies are applied to the system.

Fig. 5. (Color online) CW/CCW demodulation and the locking scheme when different modulation frequencies are adopted.

Fig. 6. CW modulation and demodulation system.

Fig. 7. SPR measurement of the cavity.

Fig. 8. (Color online) Curves obtained in the experiments. (1) The PZT driving voltage on the laser; (2) the intensity output detected by PD; (3) the demodulation of the cosine term of Eq. (3); (4) the demodulation of sine term of Eq. (3).

Fig. 9. (Color online) Demodulation curves obtained from experiments. The CW and CCW modulation frequencies are 3.5 MHz and 3.56 MHz, respectively. The right window is the magnification of the part in the ellipse.

Fig. 10. (Color online) Comparison of experiment results. The value of curve (1) is shown by the right axis while curve (2) is shown by the left axis.