Silicon-on-insulator (SOI) waveguides with different geometries have been employed to design various integrated optical components. Reducing the bending radius of the SOI waveguides with low bending loss is essential in minimizing the footprint of light-wave circuits. The propagating mode is less confined in the core of the ultra-thin SOI waveguide and penetrates to substrate and cladding, leading to higher bending loss compared to conventional SOI waveguides with a thicker guiding layer. Although various bending mechanisms have been utilized to reduce the bending loss of conventional SOI waveguides, the ultra-thin SOI waveguide bends have not been studied in detail. In this paper, we present a 60-nm-thick SOI waveguide bend based on the truncated Eaton lens implemented by varying thickness of the guiding layer. The three-dimensional full-wave simulations reveal that the designed waveguide bend, with a radius of 3.9 μm, reduces the bending loss from 3.3 to 0.42 dB at the wavelength of 1550 nm. Moreover, the bending loss for the wavelength range of 1260–1675 nm is lower than 0.67 dB while the bending loss in the C-band is lower than 0.45 dB.

具有不同几何形状的绝缘体上硅（SOI）波导已用于设计各种集成光学组件。以最小的弯曲损耗来减小SOI波导的弯曲半径对于最小化光波电路的占地面积至关重要。传播模式不太局限在超薄SOI波导的芯中，并且穿透到衬底和包层，与具有较厚引导层的常规SOI波导相比，导致更高的弯曲损耗。尽管已利用各种弯曲机制来减少常规SOI波导的弯曲损耗，但尚未对超薄SOI波导的弯曲进行详细研究。在本文中，我们提出了一种基于60纳米厚的SOI波导弯头，该弯头基于通过改变引导层厚度而实现的截顶伊顿透镜。三维全波仿真显示，设计的波导弯曲半径为3.9μm，在1550 nm波长处将弯曲损耗从3.3 dB降低到0.42 dB。此外，在1260–1675 nm波长范围内的弯曲损耗低于0.67 dB，而C波段的弯曲损耗低于0.45 dB。