Nano mode converter using dynamic refractive index modulation

Active nanophotonic devices play an important role in optical communication systems. Improving modulation efficiency and reducing the footprint of these devices are crucial for low energy information processing and on chip communication. The Multi Frequency-Domain Finite Difference (MF-FDFD) algorithm was invented to address the inherent the large difference in scale between the modulation frequency and the frequency of optical waves of active nanophotonic devices. However, due to the fact that the MF-FDFD algorithm itself requires solving a large number of unknowns compared to traditional FDFD algorithms, the current MF-FDFD algorithm still stays in two-dimensional and is difficult to calculate in three-dimensional. To solve this problem, we introduced Newton and Born methods to accelerate and complete the the solution of algorithm, and developed a three-dimensional MF-FDFD algorithm. We validated our algorithm by simulating a mode converter. Our algorithm can effectively perform first principles simulations for active nanophotonic devices, laying the foundation for future intelligent inverse design.