Ultracompact Photonic Structure Design for Strong Light Confinement and Coupling Into Nanowaveguide
Ultracompact Photonic Structure Design for Strong Light Confinement and Coupling Into Nanowaveguide
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DOI：
10.1109/jlt.2018.2821361
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发表时间：
2018-07
影响因子：
4.7
通讯作者：
M. Turduev;E. Bor;Çagri Latifoglu;I. Giden;Y. S. Hanay;H. Kurt
中科院分区：
文献类型：
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作者：
M. Turduev;E. Bor;Çagri Latifoglu;I. Giden;Y. S. Hanay;H. Kurt
最近，不同的优化算法被用来设计和改进许多纳米光子结构的性能。提出了一种基于机器学习的紧凑型光子结构的设计方法。将三维时域有限差分方法与机器学习算法相结合，设计了一种光子结构。具体地说，工作在电信波长的亚波长聚焦透镜结构被设计成具有期望的光束特性，例如在0.155λ的半最大值处的亚波长全宽度和在焦点处抑制的旁瓣电平，其中λ表示入射光的波长，等于1550 nm。所设计的紧凑型透镜结构的基片厚度为280 nm，占地面积为{\Text{2}}×{\Text{1}}，是目前为止最小的亚波长聚焦光子透镜。利用离散傅里叶变换对所设计透镜结构的二维介电分布进行了分析，解释了该透镜结构的聚焦机理。研究还表明，由于这种透镜结构具有很强的光限制特性，通过在透镜结构的输出面上集成一个宽度为200 nm的纳米波导管，可以作为光波导光耦合器件，其波束压缩比为10：1。在1550 nm波长下，光耦合器件的归一化传输效率高达0.62。研究结果表明，机器学习有助于设计高效的紧凑型光子结构。
Different optimization algorithms have recently been utilized to design and improve the performance of many nanophotonic structures. We present the design of a compact photonic structure by an approach based on machine learning. Three-dimensional finite-difference time-domain method is integrated with a machine learning algorithm in order to design a photonic structure. In particular, a subwavelength focusing lens structure that operates at telecom wavelengths is designed to have desired beam properties such as subwavelength full-width at half-maximum value of 0.155 λ and suppressed side-lobe levels at focal point, where λ denotes the wavelength of incident light and equals to 1550 nm. The designed compact lens structure has the footprint of ${\text{2}}\times {\text{1}}\,{\mu} {\text{m}}^{\text{2}}$ with a slab thickness of 280 nm, which is the smallest photonic lens for subwavelength focusing of light to date comparing to its conventional ones. The focusing mechanism of designed lens structure is explained with the help of applying discrete Fourier transform to the two-dimensional dielectric distribution of the structure. It is also shown that, due to its strong light confinement property, the designed lens structure can be used as a waveguide-to-waveguide optical coupling device with a beamwidth compression ratio of 10:1 by integrating a nanowaveguide with the width of 200 nm to the output surface of lens structure. Normalized transmission efficiency of the optical coupling device is calculated as high as 0.62 at the wavelength of 1550 nm. The outcomes of the presented study show that machine learning can be beneficial for designing efficient compact photonic structures.