Research And Application Of Silicon-Based Optical Phased Array Chip

Two-dimensional beam steering with silicon-based optical phased array(OPA)can achieve chip-level beam shaping,wide-steering-range high-resolution beam steering and flexible and accurate beam pointing.Additionally,it does not contain any mechanical parts,indicating robust performance.Therefore,it has important applications in many fields such as LIDAR,optical wireless communication,topographic mapping,projection display and so on.In this thesis,the research of silicon-based optoelectronic integrated OPA chip is carried out to optimize the steering range and beam divergence for two cutting-edge applications,namely,allsolid-state LIDAR and optical wireless communication.The main contents are as follows:1.Design theory of single-beam wide-steering-angle optical antenna for OPA.The OPA optical antenna distribution theoretical model and far-field beam distribution characteristics are studied by using the finite-difference time domain and electromagnetic wave spatial diffraction theory.A nonuniform large-spacing photonic antenna design theory based on genetic algorithm is proposed to realize 180-degree single beam steering.It can avoid beam aliasing and optical power crosstalk brought by the uniform-space optical antenna.The 128-channel OPA designed by this theory achieves 140° steering range,which is the widest steering range to our best knowledge.In this chip,the transverse emitting aperture reaches 4 mm with a divergence of 0.021°.By designing a gradient-etch grating antenna,a longitudinal emitting aperture of 3 mm length is achieved with longitudinal divergence of 0.029°.2.Research and development of silicon-based optoelectronic integrated electrooptic modulation OPA chip,including angle calibration of the OPA.The effect of PN junction doping concentration and bias voltage on refractive index is investigated using silicon carrier dispersion theory.PN junction phase shifter with ultra-low power consumption and high modulation speed is designed,and the power consumption for2π phase modulation is only 1.8 μW.128-channel silicon-based optoelectronic integrated electro-optical modulated OPA chip is fabricated.And an optoelectronic test system applicable to OPA with large emitting aperture is built.Accordingly,the upper computer software based on cosine similarity algorithm and power algorithm is written for calibrating the phase distribution of OPA antennas.And the performance of the two algorithms is compared,the results show that the power algorithm achieves10.63 d B of side lobe suppress ratio in the far-field beam distribution,which proves the superiority of the power algorithm.3.Frequency modulated continuous wave(FMCW)LIDAR system based on OPA chip.For distance detection,the relationship between the field of view(Fo V)and the mainlobe power and divergence is studied.And the effect of this relationship on the detection distance is investigated.The result shows that OPA chips with chain and fishbone antenna structure achieve a distance detection of more than 100 m in the whole Fo V.For speed detection,the frequency folding problem caused by the doppler shift of the high-speed moving target is studied,and the acoustic-optical modulator is used to compensate for the Doppler shift.The maximum speed of 115.81 km/h is accurately measured.The experimental results show that the OPA with large optical aperture has the capability of transmitting and receiving signals,which can be used for both transmitting and receiving LIDAR signals,laying the foundation for the chipbased transmitting and receiving signal module in LIDAR system.4.Optical wireless communication(OWC)system based on OPA chip.For nonereturn-to-zero(NRZ)signal transmission,communication distance of 54 m,communication rate of 32 Gbps and a communication field of 100°×2° are achieved.The effect on the communication performance of the variation of the mainlobe beam quality in the Fo V is studied.Furthermore,for improving the transmission date rate,OPA chip is used for transmitting four-level pulse amplitude modulation(PAM4)signal.Communication distance of 10 m,the communication rate of 70 Gbps,and the lateral communication cover range of 100° are achieved.To our best knowledge,the communication distance,data rate and lateral communication cover range are at the highest level.Based on single-point communication,the multi-target communication is built.The result shows in the 100° Fo V beam switching time between arbitrary angles does not exceed 27 μs,demonstrating the advantage of flexible and rapid beam switching.Additionally,the multi-target communication within 0.08° at 20 m is proposed by using the high-resolution mainlobe of the OPA chip.The channel crosstalk of less than-25.2 d B.The result shows the scalability and high security of multi-target communication based on OPA chip.In summary,this thesis presents our study on the design,testing,and application of silicon-based optical phased array chips,and successfully builds FMCW LIDAR system and OWC system based on OPA chip,promoting the practical development of silicon-based optical phased array solid-state beam steering technology.