The Exact Expression of the Generation of the Sound Intensity Function Caused by the Brillouin Scattering in Optical Fibers

• Main Authors: Yu-Chiang Li, 李瑜強
• Other Authors: Chen-Wen Tarn
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3ww2xd

碩士 === 國立臺灣科技大學 === 光電工程研究所 === 106 === In this thesis, we investigate the phenomenon of photons that are incident upon an electrostrictive material to cause stimulated Brillouin scattering and the related electrostrictive effect which is the relationship between the intensity of light and the intensity of the acoustic wave induced by the changes in volume in the photoacoustic effect. Under the incidence and affection of an optical field, the electrostrictive material produces a strain which is proportional to the square of the field strength, causing the material vibrate and produce sound waves. The incident light is hence affected by the change of refractive index caused by the acoustic wave, which induces the stimulated Brillouin scattering. A set of coupling equations of sound intensity with time and space dependence can be derived by deducing the equation of motion for the acoustic pressure wave. Using this three-wave interacting nonlinear coupling equation, we can depict the interaction of how the intensity of the incident and the scattered light interact and specifically affect the amplitude of the induced acoustic wave. With the referring to the existed experimental results, a set of numerical simulation results are provided to prove the validity of the theoretical expression of the induced sound intensity function.