臺灣博碩士論文加值系統

本論文主旨在無線光通訊的架構設計，並且將本論文架構應用在高密度分波多工的雙向傳輸上，不僅可以與現有光纖網路作連接，傳輸速度亦可達到10 Gbit/s以上。本實驗設計的發射端與接收端為對稱架構，架構由光纖準直器、物鏡以及透鏡組成，其累加損耗為1.1 dB。本論文架構使用單模光纖耦光，因此使用光纖準直器來提高耦合效率，且另一個優點在於輸出的光為平行光，會使光經過遠距離傳送之後光的擴散角度不會造成太大的損耗。實驗部分，利用單一波長傳送10 Gbit/s，經過實驗後得到功率總損耗約11.36 dB，由單向與雙向的量測結果圖觀察到單雙向的誤碼率曲線趨近於重疊，可得功率償付值為0.3 dB，進一步進行分波多工雙向傳輸實驗，總共傳送8個波道，傳輸波長從1550.08 nm - 1555.72 nm，且波道間距為0.8 nm，發射端的平均功率為-6.5 dBm，在接收端的功率平均為-24.8 dBm，功率償付值約為0.75 - 1 dB之間，由眼圖以及誤碼率來觀察，可以發現單向雙向的誤碼率數值相近，且此系統總傳輸容量可達到80 Gbit/s。最後，將計算此系統的功率餘裕值與傳送距離的關係，先假設經過發射端的功率為10 dBm，此系統的接收端的最小接收功率為-20.3 dBm，加上元件以及系統的損耗後，可以用公式算出本論文的架構最遠可傳送410 m。本架構可以架設在大樓之間傳遞訊息，減少光纖的鋪設。

Optical wireless gets more and more attention in recent years. Bidirectional transmission, which may save 50% of some optical components and devices, is also attractive to telecommunication companies and people who need such service to save cost. The thesis designs and investigates some structures for optical wireless (or free-space optics, FSO) communication. The performance analysis is according to bit error rate (BER) performance and eye patterns. The structure we proposed is formed by a fiber collimator and an objective lens. The total loss of these elements is about 1.1 dB. The challenge we encounter is to align the light beam into a single mode fiber (SMF) in small numerical aperture and low acceptable angle. Thus, a fiber collimator is used to improve the coupling efficiency. It could help to converge the light beam even although the transmission distance is increases.
In experiment set up, the laser source has an emitting power of -6.5 dBm and the received power is -24.8 dBm, for each channel. The total 18.3 dB loss is attributed to the spitting/insertion loss array waveguide grating (AWG), free-space loss and other components loss. The resulted of bit error rate has a power penalty of 0.9 dB as compares to the back-to-back transmission. For the performance in lightwave subsystem evaluation, bidirectional WDM (with eight-channel for each direction) transmission system is set up. Note that the wavelengths for downstream and upstream signals are identical (i.e., wavelength reused). The wavelength ranges from 1550.08 to 1555.72 nm with channel spacing of 100 GHz (0.8 nm). Then each channel is modulated at a data rate of 10 Gbit/s in non-return-to-zero formats, with a total transmission rate of 160 Gbit/s. The power penalty with and without bidirectional transmission is less than 0.3 dB. For the link budget issue, if launched power is 10 dBm and the required received power is -20.3 dBm for 〖10〗^(-9) BER, then the link budget is 30.3 dB and the predicted longest distance is up to 410 m.

摘要.............I
Abstract........II
致謝.............III
目錄.............V
圖表索引..........VI
第一章 緒論....... 1
1.1 前言 ........ 1
1.2 研究動機...... 2
1.3 論文架構...... 3
第二章 無線光通訊原理.......4
2.1 無線光通訊架構簡圖..... 4
2.2 發射端....... 5
2.2.1光源種類.... 5
2.2.2光源安全規範. 7
2.3 傳輸通道..... 8
2.3.1吸收....... 9
2.3.2散射....... 10
2.4 接收端....... 14
第三章 元件與儀器原理介紹... 15
3.1 光纖................ 15
3.2 光纖準直器........... 18
3.1.1漸變折射率透鏡....... 18
3.2.1高斯光束............ 22
3.3 陣列波導光柵.......... 23
3.4 摻鉺光纖放大器 ........25
3.5 Mach-Zehnder調變器... 27
3.6 光檢測器............. 28
3.7 誤碼率分析............29
第四章 實驗架構............32
4.1 實驗架構..............32
4.1.1縮束架構............ 32
4.1.2架構一.............. 33
4.1.3架構二.............. 35
4.2 單一波長單向與雙向量測結果.......36
4.3 分波多工單向與雙向量測結果.......42
4.4 分波多工雙向傳輸的功率預算.......48
第五章 結論與未來展望...............51
5.1 結論 ........................51
5.2未來展望.......................52
參考文獻..........................53

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