本論文主要是以expanded-core的波導為結構，製作1×8波導分光器。使用expanded-core波導的好處是光在折射率對比高的波導裡，可同時擁有大的模態尺寸及好的侷限能力(confinement)，因此能製作出低損耗、長度短的多模干涉分光器。
論文一開始是分析高折射率對比的通道波導在單模尺寸下與光纖的耦合損耗，結果為9.45dB，是非常大的損耗，因此本論文提出expanded-core波導的概念。首先模擬分析均勻的expanded-core波導之模態、損耗以及估計以此作為1×8波導分光器所需的長度。接下來將此結構改變成不均勻的expanded-core波導，並模擬其作為1×8波導分光器的均勻度跟額外損失，結果均勻度為0.15dB、最大的額外損失為-0.22dB、總長為4700μm、與光纖的耦合損耗是0.11dB。接著針對expanded-core波導的層數及間隔做優化，找出最佳化的結構。
最後，比較以均勻expanded-core波導、不均勻expanded-core波導和通道波導作為的1×8波導分光器之效能。

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