We report a $2\times 2$ broadband and fabrication tolerant mode-evolution-based 3 dB coupler based on silicon-on-insulator rib waveguides. The operating principle of the coupler is based on the adiabatic evolution of local eigenmodes. The key element of the device is an adiabatically tapered mode evolution region, which converts two dissimilar waveguides into two identical waveguides. Contrary to conventional designs using a linear taper function where the device adiabaticity is uneven during evolution, we use the fast quasiadiabatic approach to homogenize the adiabaticity of the device, leading to a shortcut to adiabaticity. Devices with an optimized taper region of 26.3 μm are designed and fabricated in a complementary metal-oxide-semiconductor compatible process with 193 nm deep ultraviolet lithography. The measured devices exhibit a broadband $3\mathrm{dB}\pm 0.5\mathrm{dB}$ splitting within a bandwidth of 100 nm, uniformly across a 200-mm wafer, showing good tolerance against fabrication variations.

中文翻译：

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使用快速准绝热动力学的基于模式演化的绝缘体上硅3 dB耦合器

我们报告 $\mathrm{2个}\times \mathrm{2个}$基于绝缘体上硅肋形波导的宽带和可容忍的基于模式演进的3 dB耦合器。耦合器的工作原理基于局部本征模的绝热演化。该设备的关键元件是绝热锥形模式演化区域，该区域将两个不同的波导转换为两个相同的波导。与使用线性锥度函数的常规设计相反，在该过程中设备的绝热性在演化过程中是不均匀的，我们使用快速准绝热方法来使设备的绝热性均匀化，从而实现了绝热性的捷径。采用互补金属氧化物半导体兼容工艺和193 nm深紫外光刻技术，设计和制造了具有26.3μm最佳锥度区域的器件。被测设备显示宽带$3\mathrm{D\; b}\pm 0.5\mathrm{D\; b}$ 在200 nm晶圆上均匀地在100 nm的带宽内分离，显示出对制造差异的良好耐受性。