Low-crosstalk fabrication-insensitive echelle grating multiplexers and passives for the silicon photonics toolbox
Low-crosstalk fabrication-insensitive echelle grating multiplexers and passives for the silicon photonics toolbox
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用于硅光子工具箱的低串扰制造不敏感中阶梯光栅多路复用器和无源器件
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发表时间：
2015
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通讯作者：
Badhise Ben
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作者：
C. Sciancalepore;R. Lycett;Jacques;S. Pauliac;K. Hassan;J. Harduin;H. Duprez;U. Weidenmueller;D. Gallagher;S. Menezo;Badhise Ben
在这篇文章中，我们报告了100 GBASE-LR 4标准中阶梯光栅（解）复用器的设计、制造和测试，以及其他无源架构，如用于硅基光子集成电路（Si-PIC）的O波段（1.31 μm）垂直光纤耦合器和慢波波导。详细介绍了在300 nm厚SOI平台上设计的用于4 × 800 GHz间隔波分复用的两点消像散20阶中阶梯光栅（TPSG），该光栅具有极低的串扰（< -30 dB）、精确的信道间隔和优化的平均插入损耗（~ 3 dB）。采用分布式布拉格反射器（DBR）提高光栅面反射率，采用多模干涉仪（MMI）优化啁啾中阶梯光栅（PCG）实现通带平坦化。此外，200毫米CMOS试验线加工工具，包括VISTEC可变形状的电子束光刻采用的制造。此外，多路复用器的晶圆级统计数据清楚地表明，中阶梯光栅是固有的制造不敏感的加工漂移，导致在晶圆上的多路复用器性能的分散最小化。特别地，中阶梯光栅光谱响应在串扰、通道间隔和带宽方面在晶片上保持稳定，滤波器梳的波长色散被限制为仅0.8 nm，从而突出了设计、制造路径的固有鲁棒性以及建模工具的可靠性。此外，切趾一维垂直光纤耦合器，优化的多模干涉仪（MMI）和极低损耗的慢光波导进行了演示和讨论。这种1-D光栅的绝热切趾能够提供高达30的带边缘群折射率ng，其传播损耗等同于折射率状传播状态。
In this communication, we report about the design, fabrication, and testing of echelle grating (de-)multiplexers for the 100GBASE-LR4 norm and other passive architectures such as vertical fiber-couplers and slow-wave waveguides in the O-band (1.31-μm) for Silicon-based photonic integrated circuits (Si-PICs). In detail, two-point stigmatic 20th-order echelle gratings (TPSGs) on the 300-nm-thick SOI platform designed for 4x800-GHz-spaced wavelength division multiplexing featuring extremely low crosstalk (< -30 dB), precise channel spacing and optimized average insertion losses (~ 3 dB) are presented. Distributed Bragg reflectors (DBRs) are used to improve the grating facets reflectivity, while multi-mode interferometers (MMIs) are used in optimized perfectly-chirped echelle gratings (PCGs) for pass-band flattening. Moreover, 200-mm CMOS pilot lines processing tools including VISTEC variable-shape e-beam lithography are employed for the fabrication. In addition, wafer-level statistics of the multiplexers clearly shows the echelle grating to be inherently fabrication-insensitive to processing drifts, resulting in a minimized dispersion of the multiplexer performances over the wafer. In particular, the echelle grating spectral response remains stable over the wafer in terms of crosstalk, channel spacing and bandwidth, with the wavelength dispersion of the filter comb being limited to just 0.8 nm, thus highlighting the intrinsic robustness of design, fab pathways as well as the reliability of modeling tools. As well as that, apodized one-dimensional vertical fiber couplers, optimized multi-mode interferometers (MMIs) and extremely low-losses slow-light waveguides are demonstrated and discussed. The adiabatic apodization of such 1-D gratings is capable to provide band-edge group indices ng as high as 30 with propagation losses equivalent to the indexlike propagation regime.