基于硅微环反射结构集成的折叠可调氮化硅纳米线阵列波导光栅的研究

Silicon-photonics integration circuit is one of the most attractive research fields in Semiconductor communication devices. Silicon-photonics arrayed waveguide grating is the key component as a multiplexer/de-multiplexer in this integration circuit. Silicon-photonics devices have a compact size. However, the high difference of core-cladding refractive index cause a high phase error in the silicon-based arrayed waveguide grating under the current fabrication technology. The high phase error will induce a performance of high crosstalk. On the other hand, SiN-based arrayed waveguide grating has better crosstalk and polarization performances, but its size is large. The large SiN-based arrayed waveguide grating is not a good choose for silicon photonics integration and it will enhance the cost. Based on these shortcomings, this project proposal presents a novel tunable folded SiN-based nanowire arrayed waveguide grating integrated with silicon-based rings-reflectors. This novel arrayed waveguide grating has good optical performances and a relative compact size. It is important for the future research and applications of silicon-photonics integration circuits. In this project, we will study the effect mechanism research on the design and performances of integration device based on the silicon-based ring-reflectors. We also study the effect mechanism research on the performances of integration device from the low power thermo-optics heaters. And, we will develop the monolithic integration process of silicon waveguide devices and SiN waveguide devices. Finally, based on the optimization of the device structure and the process design, we fabricate and characterize the tunable folded SiN-based nanowire arrayed waveguide grating integrated with silicon-based ring-reflectors.

硅光子集成是通信领域热门研究方向之一，阵列波导光栅是硅光子集成中的关键器件。硅光子器件结构致密；但硅纳米线阵列波导光栅有串扰、偏振等问题。较低折射率的SiN阵列波导光栅具有更好的串扰和偏振性能，但其尺寸较大，不利于硅光子器件的集成和成本的降低。基于以上问题，本项目提出一种新型的基于硅微环反射结构集成的折叠可调氮化硅纳米线阵列波导光栅。这种新型集成光栅是以SiN纳米线波导为主要结构并单片集成硅基微环反射结构而成，有优良的器件性能和致密性，同时容易与现有硅光子器件进行单片集成，对硅光子集成的研究和应用有重要意义。本项目拟开展硅微环反射波导结构对集成器件在器件设计、器件性能的影响机制研究；开展硅微环与氮化硅波导集成中的制作工艺研究；开展低功耗热光调制结构设计对集成器件的性能影响机制研究；通过结构与工艺优化设计，制作基于硅微环反射结构的折叠可调氮化硅阵列波导光栅芯片，并对该集成芯片进行测试与分析。

硅光子集成是通信领域热门研究方向之一，阵列波导光栅是硅光子集成中的关键器件。硅光子器件结构致密；但硅纳米线阵列波导光栅有串扰等问题。较低折射率的SiN阵列波导光栅具有更好的串扰和偏振性能，但其尺寸较大，不利于硅光子器件的集成和成本的降低。基于以上问题，本项目提出了一种新型的基于硅微环反射结构集成的折叠可调氮化硅纳米线阵列 波导光栅。这种新型集成光栅是以SiN纳米线波导为主要结构并单片集成硅基微环反射结构而 成，有优良的器件性能和致密性，同时容易与现有硅光子器件进行单片集成，对硅光子集成的研究和应用有重要意义。通过项目支持与研究工作，我们设计并制作了常规1×16 400GHz的AWG和折叠1×15 400GHz的AWG，流片加工后通过光学测试得到常规SiN纳米线阵列波导光栅在1550nm波段的插入损耗约为 5dB，通道间隔为 3.2nm，通道间串扰小于-22dB；折叠SiN纳米线阵列波导光栅在1550nm波段的插入损耗约为 5.5dB，通道间隔 3.2nm，通道串扰 -20dB。我们还在无源折叠 SiN AWG基础上，进行了热光结构设计，加热电极采用 TiN 材料，宽度为 0.6微米，厚度为 0.1 微米，分布在阵列波导区域。每个阵列波导两侧均有热电极平行分布，热电极离波导水平间距为1微米。所有阵列波导上的电极为串联形式。为防止产生的热相互影响以及降低功耗，隔离槽结构被设计并分布在每根阵列波导和加热电极外侧；测试结果显示串扰和插入损耗与无源折叠AWG基本相同，分别为约-20dB和5.5dB；施加电压其峰值向长波方向偏移，偏移率约为0.3nm/V。最终获得低功耗、中心波长可调的折叠SiN纳米线阵列波导光栅。此项目的研究对AWG在光通信领域的应用有着积极意义，由于可以有效减小器件的尺寸，在实际用于中可以大幅降低器件的成本；同时由于具有可调性能，可以降低Si基器件在制作过程中对工艺容差的要求。