Study On The Mechanism Of Integrated Acousto-optic Interaction At Ultrahigh Frequencies

With the increase of transmission capacity in optical communication and information processing system,traditional information technology cannot meet the demand of ultra-high processing speed in the future development.Integrated optics has the advantages of small size,high efficiency,low power consumption,stable performance and ultra-high bandwidth,which conforms to the development trend of information technology.A acousto-optic waveguide device is important in integrated optics,with high extinction ratio,low driving power,flexible design,which have a better balance between high speed and small size,can also be fabricated on almost all of the optical waveguide material system.However,the traditional integrated waveguide acousto-optic devices can not reach a high operating frequency(less than 1GHz),so they are difficult to meet the needs of information technology development.In this paper,a research about integrated acousto-optic interaction is carried out with high frequency.The research contents are as follows:(1)A structure of AlN/SiO₂/Si composite membrane is taken as an example,an analysis model for surface acoustic wave structure model is established in the COMSOL finite element simulation with structural boundary conditions and electrical boundary conditions,and the mesh division of the structure is analyzed and solved.(2)The characteristics of high frequency SAW mode is analyzed.An acoustic mode of high frequency SAW is developed,the change of phase velocity and electromechanical coupling coefficient for high mode is presented for different acoustical wavelength.For a fixed SAW with high frequency,the electromechanical coupling coefficient is discussed.An analysis is developed to have a high electromechanical coupling coefficient for high-mode SAW.(3)The mechanism of acousto-optic interaction is studied with high frequency.Based on the periodic distribution of acoustic intensity across an optical waveguide,the expression of acousto-optic overlap is improved,and the analysis model of acousto-optic interaction with high frequency of SAW is established.