The optical phased array consisting of multilevel GaAs/AlGaAs waveguides is analyzed in simulation and experiment. With the help of a novel photon design and simulation software,the finite element method and 2.5-dimensional finite-different time-domain (FDTD) are used to simulate the electrical and optical properties of the device respectively. The results indicate that the built-in electric field of the waveguide core has an influence on the total electric field and the property of emerging beam. The built-in electric field is up to 2.53×106 V/m with the p-i-n structure. The phase modulation is up to 2π with a reversed bias voltage (-10 V) applied to the device with 2416 μm long. Basing on single-mode structure, the coupling effect between adjacent cores is also taken into consideration. The influence of refractive index difference on the coupling length is also demonstrated and the proper effective index difference of 0.1 is given.