Controllable Amplified Photonic Topological Insulators for New-Architecture Wireless Systems

Photonic topological insulators (PTIs) offer immunity against defects and pave a way for high-performance devices. Despite the well-established theory behind PTIs, cutting-edge active PTI devices and systems are highly demanded. Here, we propose an amplified PTI (APTI) system that combines the protected edge states, controllable gain, signal modulation, and wave radiation in single platform. The proposed APTI is based on a topological photonic waveguide inserted with amplifier circuits, which can break the time-reversal symmetry and enhance the topological protection enormously. The unidirectional edge transmission is amplified, while the reflection toward the opposite direction is forbidden. An effective photonic model is presented to mimic the unidirectional amplification process, where both gain and gyromagnetic media are utilized. The APTI can be further tuned to achieve multifunctional modulations, and the open terminal of the waveguide directly radiates electromagnetic signals without additional antennas. Based on these unique features, an APTI-architecture wireless system is presented and experimentally verified, showing the advantages of information transfer in unidirectional and pure-mode wave systems. Our work opens up possibilities for highly integrated versatile wireless communication systems and networks based on APTIs.