| Summary: | 碩士 === 南台科技大學 === 光電工程系 === 101 === In this thesis, a homemade Zn-Indiffused lithium niobate (LN) phase modulator employed in a common-path homodyne interferometer which is proposed to explore the concentration measurements of achiral solutions by utilizing the phenomenon of reflective polarization rotation (RPR). The developed simple RPR phase measurement system is performed in LabVIEW-based platform which is used to signal acquisition and data analysis.
The simulations of optical parameter measurements are proposed according to the RPR principles. Two applications are mainly focused on the refractive index measurements of optically isotropic plates and liquid solutions. The measurement performance of concentration variations depending on the incident angles and plates (LN, TiO2, Glass) has been studied for different liquids.
In the experiments, LN plate is adopted for the reflection boundary. It is found that the similar trends between the simulations and experimental results for the measurements of different concentrations of glycerol. The incident linear polarization is changed helically through the reflection under the different related refractive index changes. The trace of linear polarization is anticlockwise rotation with a convergent spiral when the concentrations changed from low to high. Otherwise, the trace is reverse with a divergent spiral when the concentrations changed from high to low.
By the way, the dual channel phase modulator is fabricated in the Zn-Indiffused LN substrate. The characteristics of polarization-dependence loss and electro-optic modulation are discussed according to the experimental results. The results show that the phase modulated channels can be expanded by using the multiplexed signal processing system. The phase measurement errors caused by the waveguide fabrication issues of polarization dependent loss can be improved by the homodyne technique performed in LabVIEW platform. It will be possible that the multi-channel phase modulated waveguides integrated with waveguide sensors can enhance the wide functions of the optical sensing chips.
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