Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits
Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits
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DOI：
10.1364/ol.44.002314
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发表时间：
2019-05-01
期刊：
影响因子：
3.6
通讯作者：
Marko, Loncar
中科院分区：
文献类型：
--
作者：
He, Lingyan;Zhang, Mian;Marko, Loncar
集成铌酸锂（LN）光子电路近年来在高速调制、非线性频率转换和频率梳生成等高级光子功能中成为有前途的候选者。对于实际应用，具有低光纤到芯片耦合损耗的光接口是必不可少的。到目前为止，光纤到芯片的损耗（通常为10db /facet）已经主导了典型LN光子集成电路的总插入损耗，其中片上损耗可以低至0.03-0.1 dB/cm。在这里，我们通过实验证明了一种低损耗模式尺寸转换器，用于标准透镜光纤和亚微米LN肋波导之间的耦合。该耦合器由两个反向锥形组成，可将肋波导的小光学模式转换为LN纳米线的对称制导模式，具有与锥形光纤相匹配的更大模式面积。测量的光纤-芯片耦合损耗低于1.7 dB/facet，具有高制造公差和可重复性。我们的研究结果为实际集成LN光子电路与光纤的有效接口打开了大门。(C) 2019美国光学学会
Integrated lithium niobate (LN) photonic circuits have recently emerged as a promising candidate for advanced photonic functions such as high-speed modulation, nonlinear frequency conversion, and frequency comb generation. For practical applications, optical interfaces that feature low fiber-to-chip coupling losses are essential. So far, the fiber-to-chip loss (commonly > 10 dB/facet) has dominated the total insertion losses of typical LN photonic integrated circuits, where on-chip losses can be as low as 0.03-0.1 dB/cm. Here we experimentally demonstrate a low-loss mode size converter for coupling between a standard lensed fiber and sub-micrometer LN rib waveguides. The coupler consists of two inverse tapers that convert the small optical mode of a rib waveguide into a symmetrically guided mode of a LN nanowire, featuring a larger mode area matched to that of a tapered optical fiber. The measured fiber-to-chip coupling loss is lower than 1.7 dB/facet with high fabrication tolerance and repeatability. Our results open the door for practical integrated LN photonic circuits efficiently interfaced with optical fibers. (C) 2019 Optical Society of America