Photonic crystal broadband 1×N beam splitter with designable splitting ratio based on genetic algorithm

Abstract

Abstract A novel broadband Y-shaped 1×N beam splitter based on two-dimensional photonic crystal is proposed in this paper. Firstly, a broadband 1×2 beam splitting structure with designable splitting ratio is proposed. The influence of the offset along the z-axis of the dielectric rods adjacent to the input and output waveguides, and the offset of the dielectric rods at the junctions on the broadband performance of the 1×2 splitting structure is studied. Then, based on the structure, the broadband 1×4 and 1×8 beam splitters with designable splitting ratio are proposed. According to the target of the specific performance, using genetic algorithm, the broadband 1×4 and 1×8 beam splitters with different splitting ratios can be inversely designed, which not only improves the optimization efficiency, but also achieves excellent broadband splitting performance. The results show that the 1×4 beam splitters proposed have the additional loss less than 0.352dB and the response time less than 0.2ps within 1515~1590nm. The 1×8 beam splitters proposed have the additional loss less than 0.382dB and the response time less than 0.3ps within 1519~1587nm. Due to the advantages of broad operating bandwidth, flexible design of splitting ratio, high transmittance and fast response speed, the proposed 1×N beam splitters have wide application prospects in the fields of photonic integrated circuits, passive optical net-work, etc. PACS: 42.79.Fm, 42.70.Qs, 42.82.Et