[论文解读] Enhanced nonlinear optical figure-of-merit at 1550nm for silicon nanowires integrated with graphene oxide layered films

Yuning Zhang, Jiayang Wu+6 more|arXiv (Cornell University)|Apr 17, 2020

Advanced Fiber Laser Technologies参考文献 60被引用 32

一句话总结

该论文表明，在SOI硅纳米线表面覆盖分层石墨烯氧化物薄膜显著增强Kerr非线性，将非线性参数提高16倍，非线性量纲提升约20倍，达到超过5。

ABSTRACT

Layered 2D GO films are integrated with silicon on insulator (SOI) nanowire waveguides to experimentally demonstrate an enhanced Kerr nonlinearity, observed through selfphase modulation (SPM). The GO films are integrated with SOI nanowires using a large area, transfer free, layer by layer coating method that yields precise control of the film thickness. The film placement and coating length are controlled by opening windows in the silica cladding of the SOI nanowires. Owing to the strong mode overlap between the SOI nanowires and the highly nonlinear GO films, the Kerr nonlinearity of the hybrid waveguides is significantly enhanced. Detailed SPM measurements using picosecond optical pulses show significant spectral broadening enhancement for SOI nanowires coated with 2.2 mm long films of 1 to 3 layers of GO, and 0.4 mm long films with 5 to 20 layers of GO. By fitting the experimental results with theory, the dependence of the n2 for GO on layer number and pulse energy is obtained, showing interesting physical insights and trends of the layered GO films from 2D monolayers to quasi bulk like behavior. Finally, we show that by coating SOI nanowires with GO films the effective nonlinear parameter of SOI nanowires is increased 16 times, with the effective nonlinear figure of merit (FOM) increasing by about 20 times to greater than 5. These results reveal the strong potential of using layered GO films to improve the Kerr nonlinear optical performance of silicon photonic devices.

研究动机与目标

• 通过石墨烯氧化物（GO）分层薄膜提升SOI纳米线波导的Kerr非线性。
• 开发大面积、无转移的逐层涂覆方法以控制GO薄膜厚度和摆放位置。
• 通过毫微秒脉冲的自相位调制测量量化Kerr非线性增强。
• 提取GO层数与脉冲能量对n2的依赖，以理解从单层到准块状的GO行为。
• 评估对实际硅光子学器件非线性量纲的影响。

提出的方法

• 使用大面积、无转移的逐层涂覆工艺将GO分层薄膜集成到SOI纳米线中。
• 通过在SOI纳米线的二氧化硅包覆层中创建窗口来控制GO薄膜厚度与摆放位置。
• 使用皮秒光脉冲进行自相位调制（SPM）测量以评估光谱展宽。
• 将实验SPM数据拟合到理论模型以提取随GO层数与脉冲能量变化的有效n2。
• 比较不同GO层数（2.2 mm薄膜1–3层；0.4 mm薄膜5–20层）下Kerr非线性改进，揭示从单层到准块状行为的趋势。

实验结果

研究问题

• RQ1 将GO分层薄膜与硅纳米线的集成如何在1550 nm处影响Kerr非线性？
• RQ2 GO层数与脉冲能量对非线性折射率n2有何依赖？
• RQ3 GO薄膜是否能显著提升硅纳米线器件在实际光子学中的非线性量纲？
• RQ4 GO层厚度与SOI纳米线中SPM引起的光谱展宽之间存在何种关系？

主要发现

• GO涂覆的SOI纳米线由于与GO薄膜的强模式重叠，显著提升Kerr非线性。
• 从SPM引起的光谱展宽在GO薄膜长度（2.2 mm）和层数（1–3层；0.4 mm与5–20层）下增加。
• 拟合结果表明GO的n2依赖于层数与脉冲能量，揭示从二维单层向准块状行为的转变。
• SOI纳米线的有效非线性参数在涂覆GO薄膜后提升了16×。
• 有效非线性量纲（FOM）提升约20×，达到>5。