Fig. 1. Frequency-stabilized laser system based on MTS

Fig. 2. Saturation absorption spectrum signal and corresponding MTS signal when modulation frequency is 6 MHz. (a) Saturated absorption spectroscopy signal; (b) modulation transfer spectroscopy signal

Fig. 3. MTS signal under different detection powers

Fig. 4. Change of peak-to-peak value and slope of MTS signal corresponding to different parameters of modulation and demodulation signal. (a) Peak value and slope of MTS signal at different modulation frequencies; (b) peak values of MTS signal in different demodulation amplitudes

Fig. 5. MTS signal after optimization

Fig. 6. Spectrum of beat note of system and OFC

Fig. 7. Analysis of beat frequency stability. (a) Signal of beat note collected by frequency counter for 1 h; (b) Allan variation of beat note, repeat frequency, hydrogen maser frequency, and envelope frequency