A simple low-loss fiber coupling structure consisting of a Si inverted-taper waveguide and a 435 nm wide and 290 nm thick SiN waveguide was fabricated with fully complementary metal-oxide semiconductor (CMOS)-compatible processes. The small SiN waveguide can expand to the optical field corresponding to a fiber with a mode-field diameter of 4.1 µm. The fiber-to-chip coupling losses were 0.25 and 0.51 dB/facet for quasi-TE and quasi-TM modes, respectively, at a 1550 nm wavelength. Polarization-dependent losses of the conversion in the Si-to-SiN waveguide transition and the fiber-to-chip coupling were less than 0.3 and 0.5 dB, respectively, in the wavelength range of 1520–1580 nm.

中文翻译：

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用于硅光子平台的简单且完全兼容CMOS的低损耗光纤耦合结构

使用完全互补的金属氧化物半导体（CMOS）兼容工艺制造了一个简单的低损耗光纤耦合结构，该结构由一个Si倒锥形波导和一个435 nm宽，290 nm厚的SiN波导组成。较小的SiN波导可以扩展到对应于模式场直径为4.1 µm的光纤的光场。在1550 nm波长下，准TE模式和准TM模式的光纤到芯片耦合损耗分别为0.25和0.51 dB /小平面。在1520至1580 nm的波长范围内，Si到SiN波导过渡和光纤到芯片耦合中转换的偏振相关损耗分别小于0.3 dB和0.5 dB。