超高頻光毫米波產生與60-GHz光載微波無線訊號系統

Abstract

隨著科技的發展，毫米波訊號的產生與應用更為受到重視。毫米波訊號不只可應用於寬頻無線訊號傳輸，更可利用於雷達系統、汽車防撞系統、天文應用與毫米波顯像系統。然而，由於在空氣與銅導線之中的高傳輸損耗，毫米波訊號的產生與傳送依然存在許多挑戰。因此，利用低損耗的光纖網路並配合光倍頻技術，光毫米波訊號產生技術吸引各方的注目。 在這份論文當中，我們提出了使用四倍頻、八倍頻以及12倍頻的光毫米波產生技術，並使用理論以及實驗來分析及驗證系統。所提出之架構，可以產生超高頻、高純度之光毫米波訊號，提供給不同之毫米波應用使用。 基於所提出之光毫米波產生與光昇頻系統，我們可以將其利用於60-GHz光載微波無線訊號系統，並傳輸超過數個Gbps的訊號。在同時利用電與光昇頻技術，我們提出了Tandem-Single Sideband與六倍頻的60-GHz系統。在這些系統當中，我們達成了21-Gbps的訊號傳輸，並且在經過25公里光纖傳輸之後，並無明顯的訊號損耗。我們同時也提出，利用強度調變直接偵測(IMDD)的60 GHz RoF系統。系統架構非常簡單的IMDD系統，產生雙旁帶的訊號，因此將有光纖色散所造成之訊號衰退現象，在本論文中也有詳細之討論。利用IMDD的系統，我們達成60-GHz全雙工雙向21-Gbps訊號傳輸，並且達成500公尺光纖與10公尺無線傳輸。此IMDD系統，將可應用於短距離室內60-GHz RoF系統。 在本論文中，我們也同時提出整合有線基頻傳輸與光載微波無線訊號之整合型擷取網路系統。所提出之架構，可同時提供射頻M-array PSK訊號，與基頻OOK訊號。並且在遠端節點不需窄頻的光濾波器，將射頻與基頻訊號作分離，因此將可相容於現存的被動光纖網路(PON)架構之中。所提出之架構，在經過25公里光纖傳輸之後，基頻OOK與射頻PSK訊號，皆沒有明顯因光纖傳輸所造成之訊號衰減現象。

With the rapidly developing of technologies, optical millimeter-wave signal generation attracts a lot of interests for various kinds of applications. Not only in broadband wireless communication systems, but high frequency millimeter-wave signals can be utilized in radar, car anti-collision system, radio astronomy and imaging. However, millimeter-wave signal generation and transmission still remain great challenges due to the high propagation loss in air and in copper cables. Based on the extremely low loss of the optical fiber, generation of optical millimeter-wave signal with frequency multiplication attracts a lot of attentions. In this dissertation, optical millimeter-wave signal generation with frequency quadrupling, octupling and 12-tupling are proposed, theoretically analyzed and experimentally demonstrated. Optical millimeter-wave signals with ultra-high frequencies and high undesired optical sideband suppression ratios can be generated using low-frequency optical modulator, components and equipments. Because the high undesired optical sideband suppression ratios, high purity millimeter-wave signals can be generated and suitable for various kind of millimeter-wave applications. Based on the optical millimeter-wave signal generation and up-conversion systems, 60-GHz radio-over-fiber (RoF) system which provides wireless transmission with multi-Gbps data-rate can be achieved. A asymmetrical full-duplex bidirectional RoF system based on tandem-single-sideband (TSSB) modulation technique, and an optical up-conversion system with frequency sextupling for 60-GHz RoF links are proposed. Transmission of 25-km standard single mode fibers can be achieved without significant receiver power penalties. A 2 × 21-Gbps symmetrical bidirectional full-duplex system at 60 GHz based on intensity modulation direct detection (IMDD) technique which is a very simple architecture is also proposed. Although chromatic dispersion induced performance fading issues are observed in the IMDD systems due to the double-sideband (DSB) modulation scheme, 500-m fiber transmission and 10-m wireless transmission with acceptable receiver power penalties can be achieved without any dispersion compensation. Based on the very simple architectures and fully transparent characteristic of the bidirectional IMDD systems, the proposed systems are ideal for in-building high data-rate wireless applications, which are characterized by short fiber spans. Multi-service hybrid access networks which supports both RoF and fiber to the x (FTTx) systems attract a lot of interests. Two multi-service hybrid access network systems which simultaneously generate and transmit radio frequency (RF) M-array phase shift keying (PSK) signal and baseband (BB) On-Off-keying (OOK) signal are proposed and experimentally demonstrated. The wired BB signal is compatible with the existing passive optical network (PON) system, and the wireless RF PSK signal can also share the same distributed infrastructure. No dispersion induced fading issues are expected and no narrow band optical filter is needed at the remote nodes in the proposed systems. After transmission over 25-km standard single mode fiber, no significant receiver power penalties are observed in both RF and BB channels in the proposed systems.