A novel passive integrated optical circuit for mode-multiplexing and demultiplexing six channels, LP01 and LP11 modes in a few-moded fiber, is designed and tested. A push-pull solution is proposed and demonstrated to excite the LP11 modes with a high extinction ratio. The circuit can outperform present bulk-optics solutions through its compactness and stability, and it has the potential advantages of high coupling efficiency and excellent mode crosstalk suppression.
Koonen, A. M. J., Chen, H., & Raz, O. (2012). Silicon photonic integrated mode multiplexer and demultiplexer. IEEE Photonics Technology Letters, 24(21), 1961-1964. https://doi.org/10.1109/LPT.2012.2219304