論文摘要

針對工作波長於長波長(1565nm-1600nm)的摻鉺光纖放大器之低功率轉換效率以及高雜訊指數問題，在本論文中嘗試不以單純增加pump power與EDF長度的方法來提升增益，而是利用3dB coupler 製作之 Fiber Loop Mirror來作為反射信號的機制，設計使信號double pass的系統架構，使L band訊號能經過兩次放大，進而有效提升L band訊號的增益放大值，且利用兩級串接的系統設計概念，使得系統的雜訊指數決定於第一級的放大器，並將第一級放大器設計成高population inversion 的放大系統，如此一來，藉由前級摻鉺光纖放大器設計為L band信號預先放大的功能，來降低系統的雜訊指數，並且提供L band信號增益在波長上為一負斜率的增益走向，接著設計主放大器，我們嘗試用grating反射系統所產生之無用ASE(Amplified Spontaneous Emission)，並重新輸入至系統內，產生新的平衡，藉以達成抑制系統ASE的功能，使得能量能有效的留在系統內以供信號使用，而不是被ASE帶出系統外，造成能量浪費，另一方法為將主放大器拆成兩部份，其中一段EDF加以pump，而另一段則否，藉由此未pump的EDF來吸收另一段EDF的ASE，如此以使得系統ASE能更有效被利用，使效率更為提高，最後並加入一un-pump的EDF在Fiber Loop Mirror中，以用來吸收前級放大器未使用的後向ASE，使效率再進一步提高，並且藉由調整pump power大小來控制主放大器，使其呈現在波長上為一正斜率的增益走向，並與前級放大器所提供的負斜率的增益走向配合，使得信號在1565nm-1600nm波段達到增益平坦，如此將能達到一高增益，低雜訊指數，高效率，以及增益平坦的長波長摻鉺光纖放大器。

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