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arXiv 1803.08124physics.app-phphysics.optics
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光子波导模式到自由空间高斯光束的极端模式转换器

Photonic waveguide mode to free-space Gaussian beam extreme mode converter

Sangsik Kim, Daron A. Westly, Brian J. Roxworthy, Qing Li, Alexander Yulaev, Kartik Srinivasan, Vladimir A. Aksyuk

发表信息：
Light Sci Appl 7, 72 (2018)
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AI总结：

本文提出一种极端模式转换器，将光子波导模式高效转换为束腰约160微米的自由空间高斯光束，并通过两级扩展实现光栅耦合，适用于芯片级原子系统集成。

摘要：

光子芯片与原子、微机械、化学和生物系统的集成可以推动科学发展，并在芯片级器件和技术中开辟许多可能性。用于在高折射率单模波导与横截面跨越数百波长的任意自由空间模式之间直接耦合光的紧凑型光子结构，将消除笨重的光学元件，并使光子学能够集成到许多需要宽光束、结构光以及厘米级传播距离且具有低衍射极限损耗的新应用中。传统的光纤耦合方法在跨越极大的模式尺度失配（模态面积约10^6倍）时，难以实现精确、低损耗的耦合。在这里，我们提出了一种极端模式转换器，可以将光子波导模式转换为衍射极限的自由空间高斯光束，其束腰约为160微米。使用两个相同的转换器，我们演示了一种光栅到光栅的耦合，该耦合通过自由空间中的镜面反射将辐射光束耦合回芯片。我们的设计工作在780纳米波长，用于与芯片级原子蒸气腔体集成，并且可以适用于可见光、电信或其他波长。此外，通过使用本文提出的两级扩展方法，还可以实现其他类型的光束。

英文摘要：

Integration of photonic chips with atomic, micromechanical, chemical and biological systems can advance science and open many possibilities in chip-scale devices and technology. Compact photonic structures for direct coupling of light between high-index single-mode waveguides and arbitrary free-space modes spanning hundreds of waves in cross-section would eliminate bulky optical components and enable integration of photonics into many new applications requiring wide beams, structured light and centimeter-scale propagation distances with low diffraction-limited losses. Conventional fiber-coupling approaches do not scale well for accurate, low-loss coupling across the extremely large mode scale mismatch ($\approx10^6$ times in modal area). Here we present an extreme mode converter that can transform the photonic waveguide mode to the diffraction-limited, free-space Gaussian beam, with a beam waist of about $160~μ$m. Using two identical converters, we demonstrate a grating-to-grating coupling that couples the radiating beam back to the chip through a mirror reflection in free-space. Operating at 780~nm for integration with chip-scale atomic vapor cell cavities, our design can be adapted for visible, telecommunication or other wavelengths. Furthermore, other types of beams can be implemented by using the 2-stage expansion approach presented in this paper.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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