We fabricated a three-dimensional microstructured optical waveguide (MOW) in a single-crystal using femtosecond-laser writing and phosphoric acid etching techniques, and observed excellent midinfrared waveguiding performance with low loss of ∼0.5 dB/cm. Tracks with a periodic arrangement were written inside the yttrium aluminum garnet (YAG) crystal via femtosecond laser inscription, and then etched by the phosphoric acid (H3PO4) to form hollow structures. The evolution of the microstructure of tracks was investigated in detail. The function of the MOW was analyzed by different numerical methods, indicating the proposed MOW can effectively operate in quasi-single-mode pattern in the midinfrared wavelength range, which agrees well with our experiment results.

中文翻译：

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飞秒激光刻蚀磷酸刻蚀钇铝石榴石晶体中红外光子晶体波导

我们使用飞秒激光写入和磷酸蚀刻技术在单晶中制造了三维微结构光波导（MOW），并观察到优异的中红​​外波导性能，其低损耗约为 0.5 dB/cm。通过飞秒激光刻字在钇铝石榴石（YAG）晶体内部写入周期性排列的轨迹，然后用磷酸（H3PO4）蚀刻形成空心结构。详细研究了轨道微观结构的演变。通过不同的数值方法分析了 MOW 的功能，表明所提出的 MOW 可以有效地工作在中红外波长范围内的准单模模式，这与我们的实验结果非常吻合。