Study On Micro-Driving Component And Control Methods Of Optical Beam Deflection With Antiferroelectric Thick Films

In view of the existing problems of technical bottleneck, such as large occupied volume, high power dissipation, heavy nonlinear hysteresis, slow response speed, low control precision and complex control method, the fundamental research was conducted on the micro-driving components and their control methods of laser beam deflection based on the excellent characteristics of antiferroelectric thick film materials. Utlizing the effects of field-enhanced strain, near linearity before phase transition and sharp switching in the Si-based antiferroelectric material for compatible manufacturing technology of both front functional and micro-nano devices, the dissertation proposed a design method to integrate the function of laser reflection with the beam deflection for the system of space optical communication.From the perspective of the application combinating material science with MEMS optical devices, a design method was presented to join the buffer layers lattice matching to the interfacial stress releasing by multi-step annealing, in order to fabricate a large area of antiferroelectric thick film of(Pb, La)(Zr, Ti)O3(PLZT for short) on silicon substrate by heterogeneous integrated manufacture. Based on this key fabrication technology, the driving component with small sizes, slight hysteresis, rapid speed and high precision of control, helped us to discover the law of phase transition and strain behavior of antiferroelectric thick film under the electric field. A fessible control scheme was put forward when taking the PLZT micro-mirror driving component as the controlled object, and a closed-loop model was built to verify the effectiveness successfully. The jobs mentioned above can provide the theoretical basis and pratical component supports to design micro-driving devices of laser beam deflection with microminiaturization, small hysteresis and high-precision control for the system of space optical communication.The involved research contents and results are presented as follow.(1)The interfacial stress releasing technology of grain size control by multi-step annealing is presented after studying the sol-gel process to produce PLZT thick film(3μm) with induced growth and(100)-preferred orientation of silicon substrate lattice matching, so as to make the wafer-level heterogeneous integration of uniform and compact(< 3nm in surface roughness) thick films in the large area. And then the law of phase transition is discovered under the electric field, where there are useful characteristics of phase transition and effects of field-enhanced strain.(2)The compound process both dry/wet etching and reverse sputtering is studied to fibracate double layers of PLZT thick film and electrode graphically successfully, which can solve the problems how to produce PLZT driving component with small size, short response time and high precision grounded upon the mico-machining methods of MEMS.(3)The driving state factors(e.g., resonant frequency, deflection and its angle) are measured and the relations are analyzed between the designed structure, exciting voltage and unit distribution, to reveal the strain laws of the micro-mirror maded by antiferroelectric thick films and the dependence among the driving capability, the deflection angle and the frequency response.(4)According to the nonlinear hysteresis of the PLZT component of micro-mirror, two schemes of both inverse-compensation feedforward control and compound control are proposed therotically and simulatedly. The experiment results show that the compound control, integrating feedback control of PID and feedforward control of inverse-Preisach model, has good linearity between input and output and can satisfy the requirements of precise tracking control for the micro-mirror structure of PLZT.It can be concluded that the presented micro-driving component of laser deflection can be regarded, both theoretically and practically, as the high-performance one because of its microminiaturization(μm3 grade), speedy response(hundreds of nanoseconds grade), low power dissipation(dozens of voltage grade) and precise control(μrad grade).