Broadband photonic tensor core with integrated ultra-low crosstalk wavelength multiplexers
Broadband photonic tensor core with integrated ultra-low crosstalk wavelength multiplexers
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DOI：
10.1515/nanoph-2021-0752
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发表时间：
2022-02-11
期刊：
影响因子：
7.5
通讯作者：
Pernice, Wolfram
中科院分区：
文献类型：
--
作者：
Brueckerhoff-Plueckelmann, Frank;Feldmann, Johannes;Pernice, Wolfram
人工智能（AI）系统在日常生活中的集成大大增加了生成和处理的数据量。除了需要强大的计算能力之外，硬件还需要紧凑且节能。满足这些要求的一种有前途的方法是基于相变材料的光子神经形态计算，它能够实现内存计算和高度并行化。在下文中，我们提出了光子张量核心（PTC）的优化布局，该布局旨在执行实值矩阵矢量乘法并在电信波长下运行。我们采用经过充分研究的相变材料 Ge2Sb2Te5 (GST) 作为光学衰减器来执行单个正值乘法。为了将乘法推广到任意实数因子，我们开发了一种新颖的对称乘法单元，它直接包括参考计算分支。可变 GST 衰减器可在 100 nm 波长范围内实现 5 dB 的调制深度，且波长依赖性低于 0.8 dB。无源光子电路本身确保在整个波长范围内与主计算和参考计算分支的相等耦合。我们首次将波长多路复用器 (MUX) 与片上光子交叉阵列集成在一起，为完全集成的系统铺平了道路。 MUX 对于 PTC 至关重要，因为它们可以在单个光子交叉阵列中实现多个计算通道。我们通过设计基于布拉格散射的多路复用器来最大限度地减少通道之间的串扰。通过级联，我们实现了大于 61 dB 的消光比，同时插入损耗低于 1 dB。
The integration of artificial intelligence (AI) systems in the daily life greatly increases the amount of data generated and processed. In addition to the large computational power required, the hardware needs to be compact and energy efficient. One promising approach to fulfill those requirements is phase-change material based photonic neuromorphic computing that enables in-memory computation and a high degree of parallelization. In the following, we present an optimized layout of a photonic tensor core (PTC) which is designed to perform real valued matrix vector multiplications and operates at telecommunication wavelengths. We deploy the well-studied phase-change material Ge2Sb2Te5 (GST) as an optical attenuator to perform single positive valued multiplications. In order to generalize the multiplication to arbitrary real factors, we develop a novel symmetric multiplication unit which directly includes a reference-computation branch. The variable GST attenuator enables a modulation depth of 5 dB over a wavelength range of 100 nm with a wavelength dependency below 0.8 dB. The passive photonic circuit itself ensures equal coupling to the main-computation and reference-computation branch over the complete wavelength range. For the first time, we integrate wavelength multiplexers (MUX) together with a photonic crossbar array on-chip, paving the way towards fully integrated systems. The MUX are crucial for the PTC since they enable multiple computational channels in a single photonic crossbar array. We minimize the crosstalk between the channels by designing Bragg scattering based MUX. By cascading, we achieve an extinction ratio larger than 61 dB while the insertion loss is below 1 dB.