An ultra-compact mode multiplexer for TE₀, TE₁, TE₂ and TE₃ modes is proposed and demonstrated experimentally. The device is realized via pixelated waveguides with a footprint of only $5.4\times 6~\mu \,\,\text{m}^{2}$ . The measured insertion loss of the multiplexer is less than 1.5 dB. The inter-mode crosstalk is ~−20 dB at 1550 nm and below −14.6 dB from 1510 nm – 1570 nm. The fabrication and temperature tolerance of the device are investigated. The device can well tolerate the nanohole diameter variation of ±10 nm and the temperature variation of 100 K. The compactness of the proposed mode multiplexer enables potential applications in densely integrated multimode photonic circuits.

中文翻译：

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基于像素化波导的高度紧凑和高效的四模多路复用器

提出并通过实验证明了用于TE ₀、TE ₁、TE ₂和TE ₃模式的超紧凑模式多路复用器。该器件是通过像素化波导实现的，占地面积仅为 $5.4\times 6~\mu \,\,\text{m}^{2}$ . 测得的多路复用器插入损耗小于 1.5 dB。模式间串扰在 1550 nm 处为 ~-20 dB，在 1510 nm – 1570 nm 处为 -14.6 dB 以下。研究了器件的制造和温度耐受性。该器件可以很好地耐受 ±10 nm 的纳米孔直径变化和 100 K 的温度变化。所提出的模式多路复用器的紧凑性使其在密集集成的多模光子电路中具有潜在应用。