Topological beam splitter based on 2D PC with different beam splitting angles

Photonic devices are prone to reflection losses at defects and corners. Topological photonics proposes robustness of transmission to improve transmission efficiency. In this work, a dielectric photonic crystal structure based on the quantum spin Hall effect is proposed, which has a large topological bandwidth. The transmission characteristics and robustness of the topological boundary state are verified by simulation, and designed and analyzed a topological beam splitter with a beam splitting channel of 60° + 30°. The system has good light transmission stability, suppression of scattering, and defect immunity. Numerical analysis shows that the minimum transmission loss is 0.23 dB, while in the case of power equalization the minimum transmission loss is 0.29 dB. The structure has promising applications in the field of all-optical integrated circuits and is expected to promote the practical use of photonic topological insulators in the field of communications.