Fig. 1. Flow chart of frequency intermodulation phase optimization. P_i+1is the maximum value of the wave function after summing second order of frequency intermodulation; P is the smaller value of P_i and P_i+1obtained by each cycle

Fig. 2. Experimental light path diagram

Fig. 3. N=10×10 array comparison before and after optimization. (a) Intensity distribution before phase optimization; (b) Intensity distribution after phase optimization

Fig. 4. Probability density distribution diagram

Fig. 5. Simulation results. (a) Power spectrum distribution diagram before phase optimization; (b) Power spectrum distribution diagram after phase optimization

Fig. 6. (a) Details of focused beam; (b) Diffraction efficiency at different driving frequencies