Integrated waveguides with slot structures have attracted increasing attention due to their advantages of tight mode con-finement and strong light-matter interaction.Although extensively studied,the issue of mode mismatch with other strip waveguide-based optical devices is a huge challenge that prevents integrated waveguides from being widely utilized in large-scale photonic-based circuits.In this paper,we demonstrate an ultra-compact low-loss slot-strip converter with polarization insensitivity based on the multimode interference(MMI)effect.Sleek sinusoidal profiles are adopted to allow for smooth con-nection between the slot and strip waveguide,resulting reflection reduction.By manipulating the MMI effect with structure optimization,the self-imaging positions of the TE0 and TM0 modes are aligned with minimized footprint,leading to low-loss transmission for both polarizations.The measurement results show that high coupling efficiencies of-0.40 and-0.64 dB are achieved for TE0 and TM0 polarizations,respectively.The device has dimensions as small as 1.1 pm x 1.2 pm and composed of factory-available structures.The above characteristics of our proposed compact slot-strip converter makes it a promising device for future deployment in multi-functional integrated photonics systems.

State Key Laboratory of Advanced Optical Communication Systems and Networks,School of Electronics,Peking University,Beijing 100871,China;Frontier Science Center for Nano-Optoelectronics,Peking University,Beijing 100871,China;Peking University Yangtze Delta Institute of Optoelectronics,Nantong 226010,China;Peng Cheng Laboratory,Shenzhen 518055,China

[1]Zihan Tao;Bo Wang;Bowen Bai;Ruixuan Chen;Haowen Shu;Xuguang Zhang;Xingjun Wang-.An ultra-compact polarization-insensitive slot-strip mode converter)[J].光电子前沿（英文版）,2022(01):53-59

Sleek

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