Analysis And Optimization For High Quality Optical Phased Array Scanning Beam

The beam pointing control technology is widely used in the areas of laser radar, laser communications, laser television, high-speed laser printers. This kind of technology is an important section to realize a series of process on target, such as searching, acquisition, tracking, targeting and imaging. Traditional mechanical-electronic servo control system is disadvantageous in terms of portability and response speed,which was successfully overcome by phased array technology, and regarded as a major breakthrough for the radar system. Optical phased array scanning technology is a new beam directional control technology in recent studies with portability, smartness, fast beam control, high precision, no inertia and fast response. However, the existence of grating-lobe and side-lobe reduce the quality of beam and become a main bottle-neck in its application.In this paper, in a bid to solve the urgent practical problems of optical phased array scanning technology, we’ve carried out in two aspects.(1) analyze the causes of the grating-lobe and side-lobe generated from far-field optical phased array scanning beam, studied the influence parameters of the far field spot like, the array spacing, fill factor, cell diameter and shape, study different diffraction spots caused by the variety of unit calibers, provide a basic analysis for the actual phase control array scanning beam performance;(2) proposed two ways, mixed weighting method and phase compensation method, which can improve the quality of optical phased array scanning spot far-field beam.According to the basic theory of optical phased array, we get determinants of optical phased array far-field diffraction grating lobes and side lobes. Moreover, we also got the far-field diffraction intensity formula of optical phased array scanning beam side lobe suppression; Proposed hybrid weighting method based on amplitude and phase modulation; through simulation,we can get the information that when amplitude was curved, optical phased array far-field diffraction side lobes is compressed; when the value of phase-weighted is between- ? to ? compression is the best, which reduce the value from 0.9 to 0.47. Using mixed weighting method suppress optical phased array scanning beam side lobe, the relative intensity can be reduced from 80% to 20%, increased nearly 30 percent compared with density-weight and amplitude-weight. analyze how the shape of unit calibers influence the optical phased array far-field diffraction, get a variety of far-field diffraction pattern with different shapes, Taking rectangular and triangular unit aperture array for example, we simulate the 5?5 optical phased array beam far-field diffraction. Finally, we design a set of restraint apparatus based on phase compensation phased array scanning laser beam side lobe, and analyzed the advantages of it compared to irregular arrangement phased array technology.