提出了一种新型的基于渐变折射率波导自聚焦效应的模斑变换器,分析了均匀折射率波导和渐变折射率波导的模式场分布及传输特性,研究了自聚焦效应的原理。利用时域有限差分法,计算得到了该变换器的插入损耗和回波损耗,所提模斑变换器与现有的最好模斑变换器的性能相当,但长度缩短至其1/6。该新型模斑变换器可用于集成光学系统中。

A new type of spot-size converter is proposed based on the self-focusing effect of a graded-index waveguide. The field distributions and propagation characteristics of the modes in the uniform-index waveguides and the graded-index waveguides are investigated. In addition, the principle of self-focusing effect is analyzed. With the finite-difference time-domain method, the insertion loss and the return loss of the proposed converter are calculated. The performance of the proposed converter is as good as that of the existing best device, however the length of the proposed converter is reduced to 1/6 of the the existing best device. The novel spot-size converter can be used in the integrated optics.