本論文中,我們的研究目的是應用光分碼多工擷取(Optical Code Division Multiple Access, OCDMA)技術於類比/數位信號的傳輸。在光分碼多工擷取系統之中,主要的編/解碼(Codec)元件是採用光纖布拉格光柵(Fiber-Bragg Grating, FBG)所串接而成,其有著低成本的特性。因此,我們可以根據每位使用者所分配的碼字進行不同的安排,以建構出簡單的系統架構。 本研究中,首先欲傳送的類比/數位信號是經由電光轉換器(Electro-Optic Modulator, EOM)所調變。即對應的光信號將會出現在每個電光轉換器的輸出端。接著,光信號是被進行編碼經由串接而成的光纖光柵,其後通過星形耦合器並分配至所有的解碼器上。對解碼的過程,所接收的光信號是被解碼並從中擷取出對應的信息。而且,我們可以從具備良好正交性的頻譜振幅編碼(Spectral Amplitude Coding, SAC)方式中,有效減輕多重擷取干擾(Multiple Access Interference, MAI)的影響。
In this thesis, the aim of our study is to apply the optical code-division multiple-access (OCDMA) techniques to analog / digital signal transmission. Among OCDMA systems, the main encoder / decoder (codec) devices are based on a series of fiber-Bragg grating (FBGs), which has the low cost property. Accordingly, we could make different arrangements to construct the simple system architecture in accordance with each user assigned with codeword. In the study, the desired analog / digital signals are firstly modulated by the electro-optic modulator (EOM). That is, the corresponding optical signals appear at the output port of each EOM. Moreover, the optical signals are encoded via a series of FBGs and then subsequently go through star coupler distributed to all decoders. For the decoding process, the received signals are decoded and extracted the corresponding message. Also, we could get benefit from the spectral amplitude coding (SAC) scheme, which has the property of good orthogonality, to effectively mitigate the influence of the multiple access interference (MAI).