Electromagnetic metasurface design for multi-mode selective excitation in fiber communication system

How to realize the selective excitations of different optical modes in fibers is a key problem in mode division multiplexing. Here, a silicon metasurface is designed for realizing the multi-mode selective excitation at different frequencies. The metasurface is divided into four quadrants. We design the first three quadrants with the traversal searching method, and the fourth quadrant with deep learning. Consequently, two fiber modes are locked at different frequencies, and selectively excited. This proposal provides a new approach for selective excitation of fiber modes, and it can be extended to more modes. It shows promising applications in optic communications.