| Summary: | 碩士 === 國立暨南國際大學 === 應用材料及光電工程學系 === 101 === In this dissertation, optical waveguides were made by zinc (Zn) and nickel (Ni) co-diffusion on Z-cut lithium niobate substrate (ZNI: LiNbO3). The characteristics of fabrication process, diffusion behaviors and refractive index models were studied and analyzed.
In the waveguide fabrication process, Ni was used as an adhesion layer to solve the poor adhesiveness of Zn layer deposited on the substrate. In the diffusion process, the diffusion temperature was less than 850℃, so that the out-diffusion of lithium ion can be avoided. To study the diffusion characteristics, secondary ion mass spectrometry (SIMS) was measured for depth analysis at different diffusion temperature and time. Then the diffusion models of Zn and Ni co-diffusion were established.
For measurement, a modified end-fire coupling method was used for coupling the light at wavelength 1550 nm directly into the waveguides with end-facet polished. To avoid optical signal distortion during numerical differentiation when reconstructing index profile, a piezoelectric stage was used at output objective lens, and a lock-in amplifier was used for giving a sinusoidal voltage. The optical fields can then be vibrated periodically. Fourier transform was performed to retrieve the first and second-order derivatives of the optical fields for reconstruction of the refractive index profiles.
Finally, in order to find the relationship between the refractive index and diffusion model, the diffusion depth and depth of refractive index profile were both fitted. The correlation between these two depths can then be found.
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