Multichannel Parallel Mode Order Converter for On‐Chip Reconfigurable PDM‐MDM Transmission

Abstract The increasing demand for communication capacity has led to extensive exploration of hybrid multiplexing technologies that combine multiple wavelengths, modes, and polarization. Nevertheless, designing mode converters for hybrid multiplexing remains challenging. Reconfigurable and scalable multichannel parallel mode converters offer an attractive solution for efficient mode switching with a small footprint. In this paper, a compact and high‐performance dual‐polarization multichannel parallel mode order converter based on metamaterials is proposed, which consists of two components. One of the components is the flexible and compact multimode beam splitter designed by the rapidly convergent variable step size binary search algorithm. The other component is the dual‐polarization phase shifter that maximizes the feature size of the non‐subwavelength structure, significantly reducing the adverse effects of over‐etching. The experimental results demonstrate that the insertion loss of each mode is below 1.96 dB, while the crosstalk of each input mode is lower than −13.4 dB. The feasibility of high‐speed transmission is demonstrated by transmitting 30 GBuad 16‐quadrature amplitude modulation (QAM) signals on the device. This device is believed to be the first dual‐polarization multichannel parallel mode converter reported to date. This innovative device holds great potential for enhancing communication capacity in reconfigurable and scalable hybrid multiplexed transmission systems.