Beam Optimization Method For Optical Waveguide Phased Array Based On Phase Recovery

With large scan area, fast response speed and low driving voltage, optical waveguide phased array become one of the most potential research direction of laser scanning technology. Affected by the limitation of production process, the incident light and control system errors, there are obvious sidelobe in optical waveguide phased array, which cause energy dispersive and low diffraction efficiency. Therefore, the study of beam calibration and optimization methods for optical waveguide phased array is of great value in improving the beam quality of optical waveguide phased array.This paper introduces the basic principles of waveguide phased array, including the composition and control method of the optical waveguide phased array beam scanning system, and beam quality parameters. Based on electromagnetic theory of planar waveguides and the theory of waveguide coupling, the field distribution function of light in the optical waveguide array under coupling effect is given, and the beam distribution function in free space is obtained, which provides a theoretical model for the following work. Meanwhile optical waveguide array structure parameters, the incident light and driving voltage, which may affect the beam quality, is analyzed by this model. The simulation results show that the structural parameters and material refractive errors have obvious effects on the amplitude and phase distribution of the exit cross-section, resulting in beam distortion caused by the non-ideal phase distribution.In order to improve the beam quality, calibration and optimization method based on phase recovery is proposed, which includes voltage, phase alignment and beam optimization. Voltage calibration improves the accuracy of load voltage by adjusting the driving voltage control system. The phase of the exit section is recovered by far-field intensity distribution and phase calibration is realized by the relationship between the applied voltage and the actual phase. The beam is optimized by further adjusting the phase to improve the beam quality. The simulation analysis shows that when the SNR is greater than 10 d B and the receiving screen range is greater than -40 ~ 40, the error of recovery phase is less than 0.1 rad. And when the phase error is less than 0.1rad, its impact on the optimized beam quality is relatively small. This method can effectively improve the beam quality of the optical waveguide phased array, which is a key step to achieve high beam quality and high-speed scanning.