| 基于Si3N4/SiNx/Si3N4三明治结构的偏振无关1×2多模干涉型解复用器的设计 |
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| 引用本文： | 汪静丽,陈子玉,陈鹤鸣.基于Si3N4/SiNx/Si3N4三明治结构的偏振无关1×2多模干涉型解复用器的设计[J].物理学报,2020(5):102-109. |
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| 作者姓名： | 汪静丽 陈子玉 陈鹤鸣 |
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| 作者单位： | 南京邮电大学电子与光学工程学院、微电子学院;南京邮电大学贝尔英才学院 |
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| 基金项目： | 国家自然科学基金(批准号:61571237);江苏省自然科学基金(批准号:BK20151509);南京邮电大学校级科研基金(批准号:NY217047);横向课题(批准号:2017外65)资助的课题~~ |
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| 摘 要： | 提出一种基于Si3N4/SiNx/Si3N4三明治结构多模干涉波导的偏振无关1×2解复用器,用于分离1310和1550 nm两个波长.通过合理选择三明治结构中间层SiNx的折射率,可以调节同一波长两个正交偏振态的拍长相等,实现偏振无关;根据多模干涉原理,通过合理选择多模干涉波导的长度与宽度,可以使两个波长的输出像点分别成正像和反像,实现解复用功能.运用三维有限时域差分法进行建模仿真,对结构参数进行优化,并对器件关键结构参数的制作容差进行了分析.结果表明:该器件多模干涉波导的尺寸为4.6μm×227.7μm,插入损耗低至0.18dB,输出波导间的串扰低至–25.7dB, 3dB带宽可达60 nm.另外,本文提出的器件采用Si3N4/SiO2平台,可有效减小波导尺寸,提高集成度,不仅实现了偏振无关,而且结构紧凑、损耗低,在未来的集成光路中具有潜在的应用价值.
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| 关 键 词： | 多模干涉 Si3N4/SiO2平台 偏振无关 三明治结构 |
Design of polarization-insensitive 1 × 2 multimode interference demultiplexer based on Si3N4/SiNx/Si3N4 sandwiched structure |
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| Wang Jing-Li,Chen Zi-Yu,Chen He-Ming.Design of polarization-insensitive 1 × 2 multimode interference demultiplexer based on Si3N4/SiNx/Si3N4 sandwiched structure[J].Acta Physica Sinica,2020(5):102-109. |
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| Authors: | Wang Jing-Li Chen Zi-Yu Chen He-Ming |
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| Affiliation: | (College of Electronic and Optical Engineering&College of Microelectronics,Nanjing University of Posts and Telecommunications,Nanjing 210023,China;(Bell Honors School,Nanjing University of Posts and Telecommunications,Nanjing 210023,China) |
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| Abstract: | An ultra-compact 1 × 2 demultiplexer based on multimode interference(MMI) waveguide is proposed to separate the 1310 nm and 1550 nm wavelengths, in which Si3N4/SiNx/Si3N4 sandwiched structure is used to realize polarization insensitivity. Firstly, how to use Si3N4/SiNx/Si3N4 sandwich structure to achieve polarization-independent is discussed. Keeping the width of MMI waveguide WMMI unchanged, the beat lengths of two orthogonal polarization states at same wavelength versus refractive indexes of SiNx are calculated.Similar simulation curves with different WMMI values and wavelengths are also provided. The result shows that there are crossing points in the beat length curves. It means that the beat lengths for the two orthogonal polarization states at the same wavelength can be identical by choosing the proper refractive index of the SiNx.More importantly, under exactly the same premise, for the two wavelengths, their crossing points are almost identical. Then, how to realize the function of wavelength separation is studied. A variable called the beat length ratio is given, which is defined as the beat length ratio of two working wavelengths under the same polarization state. When the beat length ratio equals an even number divided by an odd number, one wavelength is even multiple of beat length and the other wavelength is odd multiple of beat length, and vice versa, that is to say, a single image and a mirror image for the two working wavelengths are formed respectively. Therefore, the two working wavelengths will output from different output ports, therefore the two wavelengths are successfully separated from each other. The demultiplexer based on Si3N4/SiO2 platform has a compact structure, easy integration and good tolerance. Three-dimensional finite-difference time-domain method is used for simulation, and the results show that the size of the MMI waveguide is 4.6 μm × 227.7 μm;the insertion loss and crosstalk are as low as 0.18 dB and –25.7 dB respectively;a broad 3-dB bandwidth of 60 nm is achieved. Moreover, the fabrication deviation of the key structural parameters about the device is discussed in detail, and the insertion loss and crosstalk are considered. To demonstrate the transmission characteristics of the demultiplexer, the evolution of the excited fundamental mode in the demultiplexer is also given. The novel demultiplexer is polarization independent and can work at wavelengths of 1310 nm and 1550 nm simultaneously. It has potential application value in future integrated optical circuits. |
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| Keywords: | multimode interference Si3N4/SiO2 platform polarization-insensitive sandwiched structure |
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