Experimental data collection methods and a corresponding numerical model are presented to investigate the quality of waveguide fabrication in nonlinear optics. The method utilises white light interferometry and standard image recognition techniques to calculate a waveguide propagation constant function. This enables comparison of a numerical second harmonic spectrum in quasi-phasematched materials, such as periodically poled lithium niobate, with the waveguide’s experimental phasematching spectrum. Using the presented method, a 3rd order polynomial fit to waveguide ridge width is demonstrated to be in good agreement with experimental phasematching spectra. The presented technique provides a nondestructive route to discriminate between issues in fabrication steps in nonlinear waveguide design.

中文翻译：

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通过二次谐波发生光谱研究 PPLN 波导均匀性

实验数据收集方法和相应的数值模型被提出来研究非线性光学中波导制造的质量。该方法利用白光干涉测量法和标准图像识别技术来计算波导传播常数函数。这使得准相位匹配材料（例如周期性极化铌酸锂）中的数值二次谐波谱与波导的实验相位匹配谱进行比较。使用所提出的方法，证明适合波导脊宽度的三阶多项式与实验相位匹配光谱非常一致。所提出的技术提供了一种非破坏性途径来区分非线性波导设计中制造步骤中的问题。