Abstract A photonic directional coupler plays a critical role in photonic integrated circuits and communication technologies, facilitating precise power distribution for multi‐channel data routing and transmission. However, conventional directional couplers face limitations in further optimizing the footprint and efficiency due to the large waveguide bending curvature and momentum mismatch between coupled waveguides. Here, a topological directional supercoupler is presented on a valley Hall silicon photonic crystal chip that achieves the shortest coupling length of 0.27 wavelength (λ) within a coupling area of 0.06λ 2 . Broadband phototunable coupling ratios are experimentally demonstrated over a bandwidth of 24 GHz with a tuning range of up to 72.8%. The dual‐channel terahertz on‐chip communication, each with a 50 Gbps data rate, further verifies the signal directional routing performance. The topological directional supercoupler provides a compact platform for topological integrated systems, promising applications in terahertz communication, interferometers, antenna arrays, and photonic neural networks.
Jia et al. (Fri,) studied this question.