Fig. 1. Principle diagram of dual-frequency laser coherent detection technology

Fig. 2. Power spectrum distributions when τ_d<τ_c. (a) Power spectrum distribution for signal with different line widths; (b) power spectrum distribution for signal with different disturbance frequencies

Fig. 3. Power spectrum distributions when τ_d?τ_c. (a) Power spectrum distributions for different line widths; (b) power spectrum distributions under different disturbance frequencies

Fig. 4. SNR curves. (a) SNR versus line width of beat frequency; (b) SNR versus noise disturbance frequency

Fig. 5. Beat signal and local oscillation signal obtained by experiment. (a)Beat signal (top) and reference signal(bottom); (b) mixing output signal

Fig. 6. Power spectra of beat signal and mixing output signal. (a) Power spectrum of beat frequency signal; (b) power spectra of mixing output signal