Energy‐Efficient Integrated Photonic Topological Devices

Topological photonics is revolutionizing the integrated electromagnetic devices, on account of the robust mode propagations immune to structural defects and sharp bends. Such robust modes have spawned attractive devices known as photonic topological waveguides (PTW), especially implemented on compact photonic‐crystal platforms. However, these exotic waveguides are challenging to be high‐efficiently interconnected with conventional integrated photonic devices. To tackle this challenge, a general energy‐efficient strategy for topological photonic structures is proposed. Such strategy is implemented onto three types of typical PTWs, which extract electromagnetic energy high efficiently from standard single‐mode rectangular waveguides. Moreover, the results of dual‐polarization valley PTW proves the polarization‐independence of their strategy. The measured near‐perfect excitation efficiencies are stable across the whole operational band of topological waveguides, thus verifying the frequency independence of this strategy. By utilizing this energy‐efficient strategy, an integrated topological high‐gain antenna, which achieves the peak directive gain of 20.25 dBi and half power beam width of 5.23° at 60 GHz, is realized. This strategy on energy‐efficient design is general to be applicable on other types of topological photonic platforms and paves the way for applications of topological electromagnetic devices. The emerging photonic topological waveguides possess the potential to revolutionize integrated photonic devices in terms of their resilience against structural defects and sharp bends. However, there lies a major problem: the low‐efficiency interconnections with conventional devices. A general energy‐efficient strategy for the interconnection between photonic topological waveguides and conventional waveguides is presented in this study.