Researchers at Peking University built hyper-spectral photonic integrated circuits based on a chain of interconnected reflective nodes, according to a study published in Nature Communications on Aug. 11, 2026. The architecture achieves superlinear complexity growth rather than the linear scaling seen in traditional photonic devices.
Conventional photonic integrated circuits scale complexity by cascading devices, an approach that becomes difficult to expand as cascade depth increases. The researchers addressed this limitation by introducing partial reflectivity to each node in the chain. By leveraging both transmissive and reflective interference inside every component node, the design expands the accessible optical delay distribution.
To manufacture the circuits, the authors created a recursive inverse-design workflow. This design method jointly optimizes node geometry and circuit topology to maximize spectral complexity. In experimental testing, a single waveguide incorporating 11 reflective nodes matched or exceeded the performance complexity of at least 100 cascaded Mach-Zehnder interferometer stages.
The system operates across a broad spectrum for optical and radio monitoring. An array of these photonic circuits successfully reconstructed optical spectra with sub-picometer resolution across an 800 nm bandwidth. This unified capability bridges optical and microwave frequencies by enabling simultaneous monitoring of both signal types within a single component.
The study was authored by Hao He, Zengji Tu, Yuanlei Wang, Hongyan Zhao, Chuangxin Feng, Yongzhuo Zhou, Yujun Chen, Ruoao Yang, Lei Zhang, Jianjun Wu, Qi-Fan Yang, and Lin Chang. The research received key equipment support from Shenzhen Golight Technology Co., Ltd. and the Institute of Semiconductors at the Chinese Academy of Sciences, alongside funding from the National Natural Science Foundation of China.
