REVIEW ARTICLE

Progress in silicon-based reconfigurable and programmable all-optical signal processing chips

Jing Xu, Wenchan Dong, Qingzhong Huang, Yujia Zhang, Yuchen Yin, Zhenyu Zhao, Desheng Zeng, Xiaoyan Gao, Wentao Gu, Zihao Yang, Hanghang Li, Xinjie Han, Yong Geng, Kunpeng Zhai, Bei Chen, Xin Fu, Lei Lei, Xiaojun Wu, Jianji Dong, Yikai Su, Ming Li, Jianguo Liu, Ninghua Zhu, Xuhan Guo, Heng Zhou, Huashun Wen, Kun Qiu, Xinliang Zhang

Front. Optoelectron., 2025, 18(2): 10.https://doi.org/10.1007/s12200-025-00154-6

Abstract:Taking the advantage of ultrafast optical linear and nonlinear effects, all-optical signal processing (AOSP) enables manipulation, regeneration, and computing of information directly in optical domain without resorting to electronics. As a promising photonic integration platform, silicon-on-insulator (SOI) has the advantage of complementary metal oxide semiconductor (CMOS) compatibility, low-loss, compact size as well as large optical nonlinearities. In this paper, we review the recent progress in the project granted to develop silicon-based reconfigurable AOSP chips, which aims to combine the merits of AOSP and silicon photonics to solve the unsustainable cost and energy challenges in future communication and big data applications. Three key challenges are identified in this project: (1) how to finely manipulate and reconfigure optical fields, (2) how to achieve ultra-low loss integrated silicon waveguides and significant enhancement of nonlinear effects, (3) how to mitigate crosstalk between optical, electrical and thermal components. By focusing on these key issues, the following major achievements are realized during the project. First, ultra-low loss silicon-based waveguides as well as ultra-high quality microresonators are developed by advancing key fabrication technologies as well as device structures. Integrated photonic filters with bandwidth and free spectral range reconfigurable in a wide range were realized to finely manipulate and select input light fields with a high degree of freedom. Second, several mechanisms and new designs that aim at nonlinear enhancement have been proposed, including optical ridge waveguides with reverse biased PIN junction, slot waveguides, multimode waveguides and parity-time symmetry coupled microresonators. Advanced AOSP operations are verified with these novel designs. Logical computations at 100 Gbit/s were demonstrated with self-developed, monolithic integrated programmable optical logic array. High-dimensional multi-value logic operations based on the four-wave mixing effect are realized. Multi-channel all-optical amplitude and phase regeneration technology is developed, and a multi-channel, multi-format, reconfigurable all-optical regeneration chip is realized. Expanding regeneration capacity via spatial dimension is also verified. Third, the crosstalk from optical as well as thermal coupling due to high-density integration are mitigated by developing novel optical designs and advanced packaging technologies, enabling high-density, small size, multi-channel and multi-functional operation with low power consumption. Finally, four programmable AOSP chips are developed, i.e., programmable photonic filter chip, programmable photonic logic operation chip, multi-dimensional all-optical regeneration chip, and multi-channel and multi-functional AOSP chip with packaging. The major achievements developed in this project pave the way toward ultra-low loss, high-speed, high-efficient, high-density information processing in future classical and non-classical communication and computing applications.

研究背景

随着大数据时代的到来，信息处理面临着容量和功耗的巨大挑战。超过90%的数据信息通过光传输，但大多数信息处理仍在电域中进行。全光信号处理（AOSP）作为一种直接在光域中处理信息的技术，相比光-电-光（O-E-O）转换，具有更高的效率、更低的成本和功耗。硅基光子集成因其与互补金属氧化物半导体（CMOS）技术的兼容性、低损耗、小尺寸和高非线性等优势，成为AOSP的一个有前景的平台。然而，AOSP在实际应用中仍面临诸多挑战，包括如何精细操控和重构光场、如何实现超低损耗的集成硅波导和显著增强非线性效应，以及如何减轻光、电和热组件之间的串扰。本文综述了我们在可重构AOSP与硅光子学结合方面所作的研究工作，这些研究有望为未来通信和大数据应用中的可持续成本和能源挑战提供解决方案。

主要内容

1.可重构滤波光子芯片

• 超低损耗硅波导和高Q微腔：通过优化制造工艺和器件结构，开发了超低损耗硅基波导和超高Q值微腔，实现了高Q值（1×106）和低损耗（0.17 dB/cm）。

• 带宽和自由光谱范围可重构的集成光子滤波器：通过热光效应和光开关，实现了从55 pm（68.6 MHz）到648.72 pm（81.09 GHz）的带宽调谐范围，以及从0.06 nm（7.5 GHz）到1.86 nm（232.5 GHz）的自由光谱范围调谐。

2.可重构逻辑运算光子芯片

• 单片集成可编程光逻辑阵列：实现了基于四波混频效应的高维多值逻辑运算，通过优化非线性波导结构，实现了100 Gbit/s的逻辑运算功能。

• 多值逻辑运算器件：基于QPSK信号的四波混频过程，实现了80 Gbit/s和100 Gbit/s的多值逻辑运算，逻辑信号的星座图清晰，逻辑序列正确。

3.多维全光再生光子芯片

• 多通道全光相位再生：利用硅波导和硅氮化物微环组成的新型光子集成架构，实现了40 Gbit/s QPSK信号的多通道全光相位再生，信噪比提升了超过6 dB。

• 基于模分复用技术的全光幅度再生：实现了在TE0和TE1模式下40 Gbit/s NRZ-OOK信号的全光再生，提升了再生容量。

4.多通道多功能AOSP芯片及封装

• 多通道和多功能AOSP芯片：实现了包含136个光子学/电子学器件的单片集成，包括滤波器、逻辑门、再生器等，总信号处理容量达到800 Gbit/s，支持多种调制格式。

• 先进的光电封装技术：开发了高密度的光电集成封装技术，包括超低损耗的光纤到芯片耦合、电子线键合和热管理。

未来展望

纳米制造技术、新型材料和封装工艺的改进有望进一步提高AOSP芯片的性能和灵活性，为光通信、高性能计算、成像和传感领域的变革性应用铺平道路。