浙江大学戴道锌团队研究了多模硅光子延迟线：突破延迟密度限制。2025年3月31日出版的《光：科学与应用》杂志发表了这项成果。

随着微波波束形成、高速光通信和集成量子光子学所需的大孔径天线和大量子阵列的出现，集成光延迟线已成为满足日益增长的需求的必要条件。由于光波导的传播损耗和群折射率之间的强烈权衡，同时实现大延迟范围、小占地面积和宽带是非常具有挑战性的。

研究组首次提出并实验证明了多模硅光子延迟线，它打破了单模波导螺旋的延迟密度限制，朝着宽带、mm²尺度和超大时间延迟的方向发展。通过展示不同偏振和模式的低损耗传播可能性，研究组引入了一种新型的多模延迟单元，该单元集成了模式（解）多路复用器和支持并行传播的TE₀、TE₁和TE₂模式的超低损耗多模波导螺旋。

TE₀、TE₁和TE₂模式的测量传播损耗为0.2dB/cm，分别为0.31dB/cm和0.49dB/cm。通过这种方式，实现了376.9 ps/cm的最高线延迟密度和0.004 dB/ps的低延迟损耗。此外，研究组实现了一个7位可调多模光子延迟线，并通过实验证明了12.7ns的超大延迟范围，延迟分辨率为100ps，占地面积为3.85mm²，延迟密度超过3299 ps/mm²，显示了迄今为止报告的片上延迟线中最大的延迟范围和最高的延迟密度。

附：英文原文

Title: Multimode-enabled silicon photonic delay lines: break the delay-density limit

Author: Hong, Shihan, Zhang, Long, Wu, Jiachen, Peng, Yingying, Lyu, Linyan, Hu, Yinpeng, Xie, Yiwei, Dai, Daoxin

Issue&Volume: 2025-03-31

Abstract: Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming, high-speed optical communication, and integrated quantum photonics. It is very challenging to achieve large delay ranges, small footprints, and broad bandwidths simultaneously due to the strong trade-off between the propagation loss and the group refractive index of optical waveguides. In this paper, we propose and experimentally demonstrate multimode-enabled silicon photonic delay line for the first time, which breaks the delay-density limit of singlemode waveguide spirals, towards a broadband, mm2-scale, and ultra-large time delay. By demonstrating low-loss-propagation possibilities for different polarizations and modes, we introduce a novel multimode delay unit by integrating the mode (de)multiplexers and the ultralow-loss multimode waveguide spiral supporting the TE0, TE1, and TE2 modes propagating in parallel. The measured propagation losses for the TE0, TE1, and TE2 modes are 0.2dB/cm, 0.31dB/cm, and 0.49dB/cm, respectively. In this way, the highest line delay-density of 376.9ps/cm and low delay loss of 0.004dB/ps are achieved. Furthermore, we implement a 7-bit tunable multimode photonic delay line and experimentally demonstrate an ultra-large delay range of 12.7ns with a delay resolution of 100ps and within an ultra-compact footprint of 3.85mm2, enabling a delay density over 3299ps/mm2, showing the largest delay range and the highest delay density among on-chip delay lines reported to date, to the best of our knowledge.

DOI: 10.1038/s41377-025-01820-2

Source: https://www.nature.com/articles/s41377-025-01820-2