Fabrication-tolerant Fourier transform spectrometer on silicon with broad bandwidth and high resolution
Fabrication-tolerant Fourier transform spectrometer on silicon with broad bandwidth and high resolution
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DOI：
10.1364/prj.379184
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发表时间：
2020-01
影响因子：
7.6
通讯作者：
Ang Li;Jordan A. Davis;A. Grieco;Naif Alshamrani;Y. Fainman
中科院分区：
文献类型：
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作者：
Ang Li;Jordan A. Davis;A. Grieco;Naif Alshamrani;Y. Fainman
我们报告了一种先进的硅基傅里叶变换光谱仪 (FTS)，与我们之前在 [Nat.通讯.9, 665 (2018)2041-1723]。我们检索了具有 0.11 THz 或亚纳米分辨率的宽带频谱（7 THz 约 193 THz），比之前演示的 [Nat.通讯.9, 665 (2018)2041-1723]。此外，它还有效解决了硅光子学中常见的波导宽度制造变化问题。该结构是一个平衡的马赫-曾德尔干涉仪，具有 10 厘米长的蛇形波导。通过使用集成加热器改变一个臂的有效折射率来引起两个臂之间的准连续光程差。蛇形臂在直线部分利用宽的多模波导来减少传播损耗，在弯曲部分利用窄的单模波导来保持占地面积紧凑并避免模态串扰。传播损耗的减少带来更高的频谱效率、更大的动态范围和更好的信噪比。此外，据我们所知，我们第一次对波导宽度的制造变化如何影响其性能进行了彻底的系统分析。此外，我们证明使用宽波导可以有效地产生可制造的器件。这项工作可以进一步为成熟的硅基 FTS 铺平道路，该 FTS 具有宽带宽（超过 60 nm）和高分辨率，适合与各种移动平台集成。
We report an advanced Fourier transform spectrometer (FTS) on silicon with significant improvement compared with our previous demonstration in [Nat. Commun.9, 665 (2018)2041-1723]. We retrieve a broadband spectrum (7 THz around 193 THz) with 0.11 THz or sub nm resolution, more than 3 times higher than previously demonstrated [Nat. Commun.9, 665 (2018)2041-1723]. Moreover, it effectively solves the issue of fabrication variation in waveguide width, which is a common issue in silicon photonics. The structure is a balanced Mach–Zehnder interferometer with 10 cm long serpentine waveguides. Quasi-continuous optical path difference between the two arms is induced by changing the effective index of one arm using an integrated heater. The serpentine arms utilize wide multi-mode waveguides at the straight sections to reduce propagation loss and narrow single-mode waveguides at the bending sections to keep the footprint compact and avoid modal crosstalk. The reduction of propagation loss leads to higher spectral efficiency, larger dynamic range, and better signal-to-noise ratio. Also, for the first time to our knowledge, we perform a thorough systematic analysis on how the fabrication variation on the waveguide widths can affect its performance. Additionally, we demonstrate that using wide waveguides efficiently leads to a fabrication-tolerant device. This work could further pave the way towards a mature silicon-based FTS operating with both broad bandwidth (over 60 nm) and high resolution suitable for integration with various mobile platforms.