With the development of highly integrated linear optical systems, both low loss and low nonlinearity are demanded for silicon slot waveguides with a small bending radius. In this paper, we calculate the variations of loss and nonlinearity with the bending radius of air-cladding and silica-cladding slot waveguides, and the mechanisms underlying the variations are revealed. We show that slot waveguides with symmetric silicon arms cannot possess low nonlinearity and low loss simultaneously due to the serious optical power leakage to the substrate. To solve this issue, asymmetric silicon arms are employed. By increasing the width of the inner arm, the high power confinement in the slot can be ensured, and this also makes the simultaneous low loss and low nonlinearity possible. We show that the silica-cladding slot waveguide under a 5 μm radius can obtain power confinement, loss and nonlinearity as respectively 40%, 1.17 × 10−4 dB/μm and 16.41/W/m, which are all comparable with those in the straight slot waveguide.

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具有低损耗和低非线性的弯曲硅槽波导

随着高度集成的线性光学系统的发展，对具有小弯曲半径的硅缝隙波导要求低损耗和低非线性。在本文中，我们计算了损耗和非线性随空气包层和二氧化硅包层缝隙波导的弯曲半径的变化，并揭示了变化的机制。我们表明，由于严重的光功率泄漏到衬底，具有对称硅臂的缝隙波导不能同时具有低非线性和低损耗。为了解决这个问题，采用了非对称硅臂。通过增加内臂的宽度，可以确保槽内的高功率限制，这也使得同时低损耗和低非线性成为可能。