In this paper, a design of a silicon mode (de)multiplexer based on cascaded counter-tapered couplers is proposed and investigated. By using the particle swarm optimization algorithm and finite difference time domain method, structural parameters of each counter-tapered coupler in our proposed mode (de)multiplexer are optimized so that high conversion efficiencies can be obtained and coupling lengths can be significantly shortened. The coupling lengths of counter-tapered couplers in the proposed silicon four-mode (de)multiplexer operating in transverse-electric polarization are 8 μm, 9 μm, and 10 μm. The corresponding conversion efficiencies are respectively 98.98%, 99.98%, and 98.68%. Experimental results show that, the fabricated device exhibits a demultiplexed crosstalk of −32.76 dB, −27.10 dB, −32.45 dB, or −33.29 dB at 1550 nm wavelength, when the fundamental transverse-electric mode is respectively launched into the ports Input0, Input1, Input2, or Input3. The measured demultiplexed crosstalk is less than −15.15 dB from 1525 to 1596 nm and lower than −18.12 dB from 1525 to 1561 nm.

中文翻译：

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基于级联粒子群优化反锥形耦合器的硅模式（去）复用器

在本文中，提出并研究了一种基于级联反锥形耦合器的硅模式（解）复用器的设计。通过使用粒子群优化算法和时域有限差分法，对我们提出的模式（解）复用器中每个反锥形耦合器的结构参数进行了优化，以获得高转换效率并显着缩短耦合长度。所提出的硅四模（解）复用器中的反向锥形耦合器的耦合长度为 8 μm、9 μm 和 10 μm。相应的转换效率分别为98.98%、99.98%和98.68%。实验结果表明，制造的器件在 1550 nm 波长处表现出-32.76 dB、-27.10 dB、-32.45 dB 或-33.29 dB 的解复用串扰，当基本横电模式分别输入端口Input0、Input1、Input2或Input3时。测得的解复用串扰从 1525 到 1596 nm 小于 -15.15 dB，从 1525 到 1561 nm 小于 -18.12 dB。