Study on anti-atmospheric turbulence interference of light borne microwave signal

In order to study effect of parameters of radio frequency(RF) intensity modulation laser signal sources, especially modulation index, on anti-atmospheric turbulence interference, phase change of the RF intensity modulation laser signal passing through atmospheric turbulence was analyzed theoretically and verified experimentally. A Mach-Zehnder interferometer was built, and two interference beams were single frequency light without modulation and dual frequency light with modulation respectively. The contrast of interference fringes was taken as the criterion of signal phase fluctuation. The contrast of interference fringes with the change of modulation depth were compared under different atmospheric turbulence conditions.The atmospheric turbulence was generated by the simulation of spatial light modulator. The contrast of interference fringes with and without atmospheric turbulence was compared under four modulation depths of 26.32%, 42.04%, 67.59% and 85.04%, respectively. The results show that, the deeper the modulation level of modulation signal is, the stronger its ability to resist atmospheric turbulence is. The conclusion has some reference significance for the selection of dual frequency lidar light sources.