On‐Chip Active Non‐Reciprocal Topological Photonics

Abstract

Abstract Chip‐scale non‐reciprocity is essential for advancing integrated photonics, particularly in realizing photonic circulators and isolators for data communication, signal modulation, and quantum computing. However, achieving a non‐reciprocal silicon chip with a small footprint, high isolation ratio, low loss, and active control remains a challenge. Here, a non‐reciprocal topological silicon chip based on magneto‐optical Indium Antimonide (InSb) integrated valley Hall system is reported. The valley‐conserved non‐reciprocal modes, realized by breaking both time‐reversal and spatial‐inversion symmetries, enable ultra‐compact and efficient non‐reciprocal photonic devices that outperform conventional chips. A maximum isolation ratio of 64.3 dB and a low chip loss of 2.6 dB is experimentally achieved by fine‐tuning the non‐reciprocal critical coupling points of a topological cavity with a small footprint of 6.4 × 2.5λ 2 . An all‐optical method is also applied to actively modulate the isolation ratio from 0 to 48 dB. The development of a non‐reciprocal topological silicon chip marks a pivotal advancement in communication systems, LiDAR, terahertz technologies, quantum computing, and cryptography.