為了建構可使用在光纖通訊系統上的高速網路封包交換機，我們必須先解決封包間相互競爭相同資源的衝突。傳統上，我們使用光-電(O-E)以及電-光(E-O)轉換來解決這個問題。首先我們把光子式的封包轉換成電子式的封包，把它們存放在電子式記憶體中。當有需要時，再把它們從電子式記憶體中取出，並轉換成光封包傳送出去。然而，上面所提的這個電子式交換機的交換速度遠遠比不上封包在光纖中所傳輸的速度。因此直覺上，全光學元件式的交換機是一個解決的辦法。然而，由於目前並沒有全光學式的隨機存取記憶體，在解決資源競爭這個問題上就會變得比較複雜。近年來，在不少研究中皆提出以光交換機與光纖延遲線來建構之二對一光學多工器。但在之前的這些研究當中，他們所提出的架構都是以多階層式的光交換機來建構光學多工器。

　　在這篇論文中，我們提出一個較為簡單、為單階層交換機的架構。我們以單一個光交換機與光纖延遲線來建構一新式二對一、先進先出(FIFO)之全光學多工器。我們考慮一個(M+2)*(M+2)之光交換機，與Ｍ條具有延遲為d_1、d_2、……、d_M 的光纖延遲線的設定。其中，這Ｍ條光纖延遲線從光交換機的Ｍ個輸出埠各自連接到Ｍ個輸入埠。剩下兩個輸入埠用來當作二對一多工器的輸入，另外兩個輸出埠則用來當作二對一多工器的輸出。

　　這樣一個設定如果滿足以下兩個條件：
(1). Ｍ條光纖延遲線的長度滿足d_1=1且d_i<=d_{i+1}<=2d_i,i =１,２,…,Ｍ－１。
(2). 我們用一特殊的方式來決定封包的路線，在本篇論中我們把它叫做C-transform。
則如此一來，我們證明這樣一個架構可操作為一個二對一、先進先出之光學多工器。

In this thesis, we propose a new construction for a 2-to-1 optical FIFO multiplexer by Switched Delay Lines (SDL).
We consider an (M+2)*(M+2) crossbar switch and M fiber delay lines with delays d_1, d_2,...., d_M.
These M fiber delay lines are connected from the M outputs of the crossbar switch to the$M inputs of the switch, leaving two inputs (resp. two outputs) of the switch for the two inputs (resp. two outputs)
of the 2-to-1 multiplexer.
We show that such a construction can be operated as a
2-to-1 FIFO multiplexer with buffer $\sum_{i=1}^{M} d_i$ if
(i) the delay lines are chosen to satisfy d_1 =1 and
d_i <= d_{i+1} <= 2d_i, i=1,2,..., M-1, and (ii)
the routing of a packet is according to a specific decomposition of the packet delay, called the C-transform in this thesis.

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