Fully-integrated Isolators for Silicon Photonics using WAMO (Wrap Around Magneto-Optics)

使用 WAMO（环绕磁光）的全集成硅光子隔离器

• 批准号: 1708887
• 负责人: Bethanie Stadler
• 金额: $ 38万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-15 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708887&HistoricalAwards=false
• 关键词: Fully; integrated; Isolators; Silicon; Photonics

Title: Fully-integrated Isolators for Silicon Photonics using WAMO (Wrap Around Magneto-Optics)Abstract: Nontechnical: Imagine an integrated circuit where light carries the signal rather than electrons. This promises to allow many signals to transmit faster, simultaneously, and without heat. The major missing link in achieving impactful applications of such "photonic integrated circuits" with high densities is an integrated isolator. Isolators use magneto-optical garnets to control the direction of light, similar to diodes in electronics. Although several integrated isolators have been proposed, they do not work for all light polarizations, and in fact the large majority only work for the polarization that is the opposite of all silicon-integrated lasers. Here, novel isolators are proposed starting with a uniquely simple design that has a high probability of success with today's lasers, and escalating to a final design that includes an integrated magnet and offers polarization diversity (meaning all polarizations can be isolated with one device). The technical novelty of this project are three-fold. First, materials challenges will be overcome to integrate magneto-optical garnets onto silicon. Second, new silicon photonic designs will initially enable the isolation of the laser-matched polarization and later the isolation of all polarizations. Third, magnetic design will be used to incorporate closed flux structures to magnetize the garnets while minimizing the magnetic cross-talk between devices.Technical: Photonic systems keep society connected with optical fibers and inside computers with optical interconnects. Photonics also impacts medicine, chemistry, and many other fields. An integrated isolator is the missing link that needs to be solved before photonic systems with fully-integrated laser sources can be a reality, and this means the results here will have very broad impact. The only passive (zero-power) way to produce a nonreciprocal device, such as an isolator, is to include a nonreciprocal (magneto-optic) material. Magneto-optic garnets (e.g., Cerium-doped Yttrium Iron Garnet) yield orders of magnitude better performance than any other material. However, these garnets are difficult to integrate with silicon as single phase films, and multiple phases cause loss. Also, isolator designs proposed to date are too large for practical implementation, and they mostly use non-reciprocal phase shift in a geometry that only applies to transverse magnetic polarizations while integrated lasers output only transverse electric light. Here, the combination of proven high-gyrotropy, low-loss, and silicon-integrated garnet films (Stadler) with novel silicon photonic designs (Li) will ensure all-passive silicon isolators with polarization diverse functionality. Three layers of innovation will be explored. First, a transverse electric isolator is proposed where garnet is deposited between the branches of an interferometer to provide a simple asymmetry such that, with one applied magnetic field, a "push-pull" non-reciprocal transverse electric phase shift will occur. The next layer of innovation will apply the fundamental photonic results from above and will extend the design to include an integrated magnetostatically-engineered magnetic bias. Specifically, a closed flux loop structure (similar to a closed horseshoe magnet) will be used to magnetize the garnet claddings without requiring an external field and without producing fringing fields in the circuit. The final step towards polarization diversity is a nearly closed flux design that will yield the first device to provide polarization diversity in an all-passive, fully-integrated isolator with wrap around magneto-optics.

标题：使用 WAMO（环绕式磁光）的全集成硅光子隔离器摘要：非技术性：想象一个集成电路，其中光携带信号而不是电子。 这有望让许多信号更快、同时传输，而且不会产生热量。要实现这种高密度“光子集成电路”的有效应用，主要缺失的环节是集成隔离器。 隔离器使用磁光石榴石来控制光的方向，类似于电子设备中的二极管。尽管已经提出了几种集成隔离器，但它们并不适用于所有光偏振，事实上大多数仅适用于与所有硅集成激光器相反的偏振。 在这里，提出了新颖的隔离器，从一种独特的简单设计开始，这种设计在当今的激光器上很有可能成功，然后升级到包括集成磁体并提供偏振多样性的最终设计（意味着可以用一个设备隔离所有偏振）。该项目的技术新颖性有三个方面。首先，将克服材料挑战，将磁光石榴石集成到硅上。其次，新的硅光子设计将首先实现激光匹配偏振的隔离，然后实现所有偏振的隔离。第三，磁性设计将用于结合闭合磁通结构来磁化石榴石，同时最大限度地减少设备之间的磁串扰。技术：光子系统通过光纤和内部计算机与光学互连保持社会连接。光子学还影响医学、化学和许多其他领域。 在具有完全集成激光源的光子系统成为现实之前，集成隔离器是需要解决的缺失环节，这意味着这里的结果将产生非常广泛的影响。 生产不可逆器件（例如隔离器）的唯一无源（零功率）方法是包含不可逆（磁光）材料。磁光石榴石（例如掺铈钇铁石榴石）的性能比任何其他材料好几个数量级。然而，这些石榴石很难以单相薄膜的形式与硅结合，多相会造成损失。此外，迄今为止提出的隔离器设计对于实际实施而言太大，并且它们大多在仅适用于横向磁极化的几何形状中使用不可逆相移，而集成激光器仅输出横向电光。在这里，经过验证的高陀螺、低损耗和硅集成石榴石薄膜（Stadler）与新颖的硅光子设计（Li）的结合将确保全无源硅隔离器具有偏振多样化功能。 将探索三个层面的创新。首先，提出了一种横向电隔离器，其中石榴石沉积在干涉仪的分支之间，以提供简单的不对称性，使得在施加一个磁场的情况下，将发生“推拉”非互易横向电相移。下一层创新将应用上面的基本光子结果，并将扩展设计以包括集成的静磁工程磁偏置。具体来说，将使用闭合磁通环结构（类似于闭合马蹄形磁体）来磁化石榴石包层，而不需要外部场，也不会在电路中产生边缘场。实现偏振分集的最后一步是近乎封闭的通量设计，这将产生第一个在具有环绕磁光的全无源、完全集成隔离器中提供偏振分集的器件。

项目成果

Interfacial and Bulk Magnetic Properties of Stoichiometric Cerium Doped Terbium Iron Garnet Polycrystalline Thin Films

• DOI: 10.1002/adfm.202000409
• 发表时间: 2020-02
• 期刊: Advanced Functional Materials
• 影响因子: 19
• 作者: Karthik Srinivasan;C. Radu;D. Bilardello;P. Solheid;B. Stadler

Diffusion-Driven Exfoliation of Magneto-Optical Garnet Nanosheets: Implications for Low Thermal Budget Integration in Si Photonics

• DOI: 10.1021/acsanm.1c02459
• 发表时间: 2021-10
• 作者: Karthik Srinivasan;Andrew D. Schwarz;Jason C. Myers;N. Seaton;B. Stadler

High-Gyrotropy Seedlayer-Free Ce:TbIG for Monolithic Laser-Matched SOI Optical Isolators

• DOI: 10.1021/acsphotonics.9b00707
• 发表时间: 2019-09
• 期刊: 2020 Conference on Lasers and Electro-Optics (CLEO)
• 作者: Karthik Srinivasan;Cui Zhang;P. Dulal;C. Radu;T. Gage;D. Hutchings;B. Stadler