微纳光波导的基本功能是实现光波的低损耗传输, 是芯片光互连的基础, 其传输损耗是评价微纳光波导加工质量和传输性能的基本指标。微纳光波导由于其尺寸比常规光波导小1～2个数量级, 光耦合的难度和不确定性都很大, 造成传输损耗的测量相对困难。探讨了可用于微纳光波导传输损耗测试表征的几种方法, 包括截断法、法布里-珀罗(Fabry-Pérot,F-P)腔谐振谱条纹对比度分析法、傅里叶(Fourier)变换法等, 对上述方法在测试精度、适用条件方面进行了分析对比。研究表明, 截断法受光纤耦合不确定性的影响测量误差较大; F-P腔谐振谱条纹对比度分析法能够消除光纤耦合不确定带来的误差, 但是只能测量单一F-P谐振腔的波导结构, 无法测量复杂的多腔结构; 傅里叶变换法能够消除波导和光纤耦合状态的不固定带来的误差, 并通过相邻峰位的比值来提取出波导的传输损耗。

The micro-nano sized waveguides are the basic building blocks for on-chip interconnects, and their basic function is to transmit light with low loss. The propagation loss is one of the indexes to evaluate the fabrication quality and performance of micro-nano sized waveguides. With cross section size one or two orders smaller than that of conventional waveguides, and due to the large uncertainty and the difficulty of light coupling, the propagation loss measurement is comparatively difficult to perform. This paper discussed several propagation loss measurement methods suitable for micro-nano sized waveguides, including cut-back method, Fabry-Pérot cavity interference fringe contrast ratio method, and Fourier transform method, etc. The analysis and comparison on the above mentioned methods in terms of measurement accuracy and applicability was given, that is, the cut-back method is liable to the uncertainty of light coupling with comparatively large error, the Fabry-Pérot cavity interference fringe contrast ratio method is immune to the uncertainty of light coupling, but only applicable to the case of single F-P cavity, the Fourier transform method is not only immune to the uncertainty of light coupling, but also applicable to the case of multi-cavity.