Key Technologies In Integrated Photonics Based Phased Array Radar

Phased array radars are widely used due to their fast beam scanning speed and high detection sensitivity.However,it is difficult to meet the radars' performance requirements in complex environments because of the narrow working bandwidth of the traditional phased array radar.The use of optical true time-delay network instead of traditional phase-shifting network can effectively improve the instantaneous bandwidth of radar and eliminate the beam deflection effect of radar.However,for a large-scale two-dimensional phased array radar,the optical true time-delay network built with discrete components are still plagued by large size and high power consumption.The optical phased array radar based on integrated photonics technology can significantly reduce system size,power consumption and of course the cost,which opens up a new path for the future development of phased array radar.The key technologies in integrated photonics based phased array radar systems are analyzed in this paper.The radio over fiber(ROF)link is modeled firstly and the performances of ROF link such as link gain,noise figure,and dynamic range are discussed.Then the basic principles and main functions of the optical true time-delay network are explained.Based on this,a true time-delay network based on silicon-based integrated binary delay line for two-dimensional phased arrays is proposed.The complexity of the network can be reduced to(N-1)/2(when N is odd)or N/2(when N is even).The control system of the optical true time-delay network is an important part of its practical application.In this paper,combined with the proposed true time-delay network,the hardware and software of the control system are designed.Different beam angles of the phased array radar can be switched reliably by the control system.Based on the above analysis and design,an implementation scheme of simultaneous multibeam large-scale phased array radar system is proposed finally.An 8×8 two-dimensional phased array radar is designed and implemented as a demonstration.The results of experimental measurement and simulation analysis show that the maximum delay mean error and root mean square error of the four BISODLs in the chip are-0.55 ps and 0.80 ps,respectively.The beam pointing error is less than 0.5° in the bandwidth of 2?8 GHz,and multiple beams can be controlled independently at the same time.The system meets the design requirements and achieves a high level of indicators.It also verifies the feasibility and advancement of the silicon-based integrated phased array radar system.