| Stimulated Brillouin scattering(SBS)can be triggered by the interaction of phonons and photons induced by optical forces in optical waveguides,which is one of the bases for optical signal acquisition,processing and storage.In traditional fiber optic systems,this nonlinear optical process has been extensively studied leading to applications such as distributed sensing,microwave photonic signal processing,and optical buffering.In the past half century,silicon photonic devices have experienced considerable development and played an important role in the field of optical communications.By using the mature semiconductor fabrication procedure,silicon photonic devices have the potential for monolithic integration.Research on the photon-phonon interaction in silicon-on-insulator(SOI)integrated waveguides will provide strong support for the next-generation high-performance sensors and all-optical signal processing.This thesis focuses on the stimulated Brillouin scattering effect induced by the interaction of phonons and photons in SOI waveguides.Firstly,we analyze the parametric process of SBS effect,explain the mechanism of the formation of light and sound waves in the waveguide,and derive the forward stimulated Brillouin scattering(FSBS)gain coefficient formula according to the quantum theory framework.Secondly,the established theoretical model is combined with finite element simulation to study the photon-phonon interaction in rectangular waveguides and slot waveguides.The contribution of electrostrictive force and radiation pressure to FSBS gain is analyzed in both waveguide structures,and the influence of the structural parameters are studied to enhance the FSBS gain respectively.Finally,a slot waveguide Bragg grating is proposed to further improve the FSBS gain based on its slow light characteristic.Simulation results show that the waveguide structure can drastically enhance the strength of the photon-phonon interaction by orders of magnitude. |
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