为了进一步探索用绝缘体上晶体硅制作的浅刻蚀脊形波导侧向泄漏损耗的规律, 提出并研究了一种非矩形截面浅刻蚀绝缘体上晶体硅脊形波导.用光的干涉理论建立该波导的周期性损耗模型并推导出损耗周期公式, 然后通过完美匹配层边界条件下的频域有限元法仿真观察该特殊波导类TM0模的侧向泄漏损耗周期的变化与最大损耗点的偏移现象.周期大小的仿真结果与理论计算符合度较高, 其平均相对误差仅0.56％.此外, 发现该类波导在某些沟槽宽度下可以通过改变截面来实现对类TM0模损耗从最大到最小的调节, 而在另外一些沟槽宽度下, 类TM0模损耗对截面变化不敏感.研究结果可以简化波导加工并提高制作容差, 为该类型波导的设计与制作提供参考.

In order to further investigate the lateral leakage loss behavior of shallowly-etched rib waveguides on silicon-on-insulator, a kind of shallowly-etched rib waveguide with non-rectangular crosssection was proposed and analyzed. A periodical loss model and a formula of loss period of this waveguide were obtained by the interference theory, and then phenomena of periodic variation of lateral leakage loss and shift of the maximum loss point for TM0-like mode were observed through the finite element method simulation in frequency domain with perfectly-matched layerconditions. The period in simulation results are highly consistent with theoretical calculation, and the average relative error is only 0.56%.In addition, it is found that TM0 mode loss can be adjusted from maximum to minimum by changing the cross section of rib waveguides with some trench widths, while TM0 mode loss is not sensitive to the change of cross section in rib waveguide with other trench widths. These findings can simplify process and improve fabrication tolerance, which provide theoretical guidance for the design and fabrication of this kind of waveguide.