| Summary: | 碩士 === 國立臺灣科技大學 === 光電工程研究所 === 104 === In this thesis, a theoretical model is proposed to evaluate the property of the spatial coherence of an electro-optic modulator. Staring from the Maxwell’s equation, the evolution and interaction of a lightwave inside the eltro-optic modulator can be properly described. In order to investigate the degree of spatial coherence of light during the electro-optic interaction, a set of coupled equations of the ordinary and extraordinary light can be derived from the Maxwell’s equations. The couple equations can be solved analytically and the evolution of the spatial coherence of light can be observed to get a general solution and simulation in applied voltage in 0~10 V.
The lightwave is assumed in the Gaussian-Schell model form and incidents on the E-O modulator and the crystal of the E-O modulator is modulated by an external electric field, therefore the refractive index is formed as a grating type. When the lightwave through the crystal, the degree of coherence can be calculated by the autocorrelation function.
We find that, under the applied voltage 0~10 V on LiNbO3 crystal, there is no significant change of the degree of coherence of the ordinary light, while a significant change of and the extraordinary light can be observed.
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