Fig. 1. Diagram of experimental device configuration with inset illustrating D₁ line transition energy levels of ⁸⁷Rb and laser modulation sidebands

Fig. 2. D₁ line transmission spectra of atomic clock cell and reference cell. (a) Reference cell saturation absorption enhanced spectrum and atomic clock cell transmission spectrum; (b) error signal obtained from modulation and demodulation corresponding to reference cell spectral line

Fig. 3. Compensated D₁ line transmission spectra of atomic cell. (a) Reference cell saturation absorption enhanced spectrum and atomic clock cell transmission spectrum; (b) error signal obtained from modulation and demodulation corresponding to reference cell spectral line

Fig. 4. D₁ line transmission spectra of atomic cell under dual-modulation. (a) Reference cell saturation absorption enhanced spectrum and atomic clock cell transmission spectrum; (b) error signal obtained from modulation and demodulation corresponding to reference cell spectral line

Fig. 5. Relationship between power of radio frequency (RF) modulation signal and slope of error signal

Fig. 6. Laser frequency noise

Fig. 7. Zeeman spectra of CPT resonances with two ground state hyperfine levels of ⁸⁷Rb. (a) CPT resonance lines with frequency shift using AOM; (b) CPT resonance line at 3.417 GHz and 200 MHz modulation