Researches On The Wideband Design Of Anisotropic Acousto-optic Deflectors Under Different Operating Modes

The diffraction of the incident laser beam induced by the periodical distribution of the refractive index of the crystal,which is caused by the propagation of the ultrasonic wave in the crystal,is defined as the acousto-optic effect.The acousto-optic device have been widely applied in the field of beam steering,optical signal processing,and imaging technology.wideband design is the precondition to ensure the high performance of the acousto-optic deflector(AOD).Although the multi-piece transducer based AOD and the cascade design of multi-piece AOD can improve the bandwidth of the device,but the disadvantages of the high process requirements and complex system are also obvious.Therefore,improving the bandwidth performance of the acoustic-optic device based on the single-piece transducer structure is the basis of the broadband design.Based on the theory of anisotropic acousto-optic interaction,the wideband design of anisotropic acousto-optic deflector using tellurium dioxide and lithium niobate are carried out under different operating modes,the main contents of this paper include the following parts:The research background and the development of acousto-optical technology are summarized,the coupling wave equation and basic principle of the acousto-optical deflector are proposed,which constructs theoretical foundation for the optimal design of the anisotropic acousto-optic devices.The wideband design of the anisotropic acousto-optic deflector under the condition of negative off-axis angle is studied.By solving the Dixon equation of the acousto-optic interaction of tellurium dioxide,the wideband parameters of anisotropic acousto-optic deflector under different frequency bands are obtained.The research results show that the bandwidth and central frequency show different properties under different frequency band,and the selection of the diffraction order also effects the characteristics of the acousto-optic deflector.The wideband design of the anisotropic acousto-optic deflector using lithium niobate under the condition of negative incident angle is studied.The wideband parameters under different ultrasonic modes are obtained,and the properties of the bandwidth and centralfrequency under different incident angle are simulated and analyzed,which provide useful references for the wideband design of the anisotropic acousto-optic deflector.The wideband design of anisotropic acousto-optic deflector using tellurium dioxide under the condition of 3dB bandwidth is studied.Two different methods are proposed for the3 dB wideband design based on unimodal curve and bimodal curve,respectively.The design parameters under different operating modes are obtained by theoretical calculation and the analytical formula are also obtained by numerical fitting,the research results are meaningful for the detailed theoretical and data reference for the wideband design of anisotropic acousto-optic deflector.