傳統光纖通訊系統因採用OOK (on-off keying) 調變方式，所以頻譜效率不佳，而有很大的改善空間。OFDM系統由於其子載波頻譜可互相重疊的特性，同時結合可攜帶多個bits的QAM調變，因此頻譜效率可大幅改善。但OFDM系統須使用DAC/ADC來產生訊號與擷取訊號，所以硬體電路的頻寬將會是決定OFDM系統是否能達到光纖通訊系統所需的高速、大頻寬的通訊容量的關鍵；而光纖通訊動輒10、20G的頻寬需求，對現今的電路技術仍是不容易克服的，因此本論文的主要目的為探討在使用OFDM系統時，如何減少對硬體電路頻寬的需求，同時提高頻譜使用效率與增大通訊容量。
本篇論文使用多頻帶 (multi-band) 系統來提升光學正交分頻多工系統的通訊容量，並減少對硬體頻寬的需求，我們提出了使用OBPF (optical bandpass filter)分別解調各個頻帶之方法，用此方法解決各個頻帶間的SSBI (signal-signal beating interference) 干擾，並以VPI驗證各個頻帶的表現相近。同時在實驗上，我們建構了將各個頻帶載在光載波兩側的傳輸端架構，並以此方式攜帶了四個頻帶，每個頻帶頻寬約4.6GHz，使用16-QAM OFDM 調變，總傳輸量達到70 Gbits/s。經解調後各個頻帶表現皆小於錯誤更正碼之極限 (BER = 3.8 *〖10〗^(-3)) 。
最後為了以單一個檢光器(photo detector)來接收多個頻帶，以減少系統成本，我們針對自我同調偵測架構作探討，提出了使用OBPF與平衡接收機 (balanced receiver) 來消除SSBI的方法，並以VPI 驗證其系統表現。

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