Abstract Titanium-diffused lithium tantalate (Ti:LT) multimode planar waveguide was produced by in-diffusion of titanium thin-film deposited onto a Z-cut congruent LT substrate. Titanium concentration (CTi) in the titanium-diffused layer was profiled by secondary-ion-mass-spectrometry. Modes guided in the waveguide were characterized by prism coupling technique. Refractive index in the waveguide is profiled on the basis of the measured mode indices, and is related to the CTi profile. The results show that both the refractive index and the CTi profiles obey to a Gaussian function. The profiles of titanium-induced extraordinary and ordinary index changes are almost identical, implying that the index change in the Ti:LT waveguide has a small anisotropy and the confinement to the mode field is polarization-insensitive. The ordinary and extraordinary index changes reveal a similar exponential dependence on the CTi with a power index of ∼0.8.

中文翻译：

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钛扩散全等钽酸锂光波导中的折射率分布

摘要 钛扩散钽酸锂 (Ti:LT) 多模平面波导是通过沉积在 Z-cut 全等 LT 衬底上的钛薄膜的内扩散制备的。钛扩散层中的钛浓度 (CTi) 通过二次离子质谱法进行分析。在波导中引导的模式由棱镜耦合技术表征。波导中的折射率根据测量的模式指数进行分布，并与 CTi 分布相关。结果表明，折射率和 CTi 分布均服从高斯函数。钛引起的异常和普通折射率变化的分布几乎相同，这意味着 Ti:LT 波导中的折射率变化具有很小的各向异性，并且对模式场的限制对偏振不敏感。