光纖網路越來越普遍，而室內無線光通訊是未來發展的趨勢，本論文的主旨主要是使用雷射源當作傳輸光源，並將光源涵蓋範圍擴大，目的是達到接收端能方便收到訊號，藉由雷射優於LED的優點，例如:線寬窄、調變頻寬大，同調性高等，達到更快的資料傳輸速率。
為了擴大雷射光源覆蓋範圍，首先將半導體雷射接續一段大數值孔徑光纖再輸出到空氣中。第三章分別量測與應用三種多模光纖包括:前兩種為纖心(core) 62.5 μm多模光纖搭配平整端面或電弧端面，第三種為core 400 μm多模光纖搭配平整端面。設計過程牽涉的參數量測包括:數值孔徑、光強度分佈，並載入訊號輸出。結果以core為62.5 μm多模光纖搭配平整端面輸出表現最好。當光源改用環型光纖雷射時，載入訊號傳輸會有極化不穩定造成訊號抖動的問題，所以本論文後續研究以半導體雷射為光源。第四章為非指向性之視線型(Non-directed LOS)傳輸通道，使用外部訊號調變方式傳輸距離為0.5 m，光源涵蓋面積約為180 cm2，當載入NRZ-OOK資料速率200Mb/s時，Q factor為11.85；指向性之視線型(Directed LOS)傳輸通道，傳輸距離為2m，利用直徑大小為7.5 cm的平凸透鏡產生近平行光，屏幕光束直徑為5 cm，光源覆蓋面積約為19.62 cm2，當NRZ-OOK資料速率為200Mb/s時，其Q factor為16.8。為了加大光束直徑涵蓋範圍以便接收器接收，將直徑7.5 cm的平凸透鏡控制發散角，產生10 cm的光束，當載入 NRZ-OOK資料速率200Mb/s時，接收端光束直徑10 cm，中心點的Q factor為15，邊緣四點則為12.36~13.12，載入4-PAM資料速率400Mb/s，誤碼率為1.99x10-7，邊緣四點則為7.98x10-7~2.92x10-6。
第五章使用直接訊號調變方式結合指向性-視線型(Directed LOS)傳輸通道，載入NRZ-OOK資料速率200Mb/s時，接收端光束直徑10 cm，中心點的Q factor為13.7，邊緣四點則為12.77~12.96，載入4-PAM資料速率400Mb/s，誤碼率為7.94x10-4，邊緣則為1.24x10-3~5.01x10-3。驗證顯示外部訊號調變比直接訊號調變好與習知的理論相符，然而直接調變有便宜簡便的優點。本章最後使用指向性視線型(Directed LOS)通道成功傳輸2 m影像訊號。第六章為結論與未來展望。

Fiber-optic network is more and more popular, while indoor optical wireless communication is future trend for the coming years. The thesis proposed the usage of lasers as light source for transmission. Beam expander method is investigated for expansion the beam diameter, to make easily signals received. Laser source has better performances in spectral width, modulated bandwidth and high coherence. So it is used to replace light emitting diode (LED) for indoor communication.
In order to expand the laser beam, we used semiconductor laser pigtail with three kinds of fibers to obtain larger diameter. The multimode fibers we discussed in Chapter three are multimode fiber with large numerical aperture (NA), multimode fiber using acr to get a ball shape end-facet. Both fibers have core diameter of 62.5μm. The third fiber has core diameter up to 400 μm with flat end-facet. The parameters concern including NA, power distribution and signal transmission characteristic. We found that the first with 62.5 μm and flat-end face has the best performance among three candidates.
We also used Erbium-doped fiber ring laser (EDFRL) as transmission light source. Some jitters phenomena were found in eye-diagram due to instability of laser polarization. Therefore, a semiconductor laser as transmission light source was selected. In Chapter four, we studied non-directed light-of-sight (LOS) transmission using external modulation. Under 0.5 meter transmission distance, the measured Q-factor is 11.85 with NRZ-OOK format and 200 Mb/s bit rate. In this case the the coverage area was about 180 cm2. On the other hand, directed light-of-sight (LOS) transmission used external modulation. Under 2 meter transmission distance, the measured Q-factor is 16.8 with NRZ-OOK format and 200 Mb/s bit rate. In this case the the coverage area was about 19.62 cm2.
We adjusted distance between fiber and lens with diameter of 7.5 cm to control divergent angle. Under this condition the laser diameter is expanded to 10 cm at 2 m away form the laser source. Again we used directed light-of-sight (LOS) transmission in external modulation. Under 2 meter transmission distance, the measured Q-factor is 15 in center and 12.36~13.12 at the four boundaries, with NRZ-OOK format and 200 Mb/s bit rate conditions. In addition, the bit error rate (BER) of 2×10-7 at center of received area and 8×10-7~3×10-6 at four boundaries were obtained under 4-PAM 400Mb/s bit rate.
In Chapter five, we investigated direct modulation integrated directed LOS configuration. Under 10 cm diameter, the measured Q factor was 13.7 at the center of received area and 12.77~12.96 at four boundaries. The format and bit rate are NRZ-OOK 200 Mb/s. In addition, the bit error rate (BER) of 7.94x10-4 at center of received area and 1.24x10-3~5.01x10-3 at four boundaries were obtained under 4-PAM 400Mb/s bit rate. The results show that external modulation has better performance than that of direct modulation. However, direct modulation has benefits of cheap and easy to handle. The video transmission was successfully demonsatred based on directed LOS communication system in 2 m distance. Conclusion and suggested further work are addressed in Chapter Six.

[1] M. J. McCullagh, P. P. Smyth, D. R. Wisely and P. L. Eardley, “Optical wireless LANs: applications and systems,” IEEE Colloquium on Cordless Computing-Systems and User Experience, pp. 8/1-8/3, 1993.
[2] P. P. Smyth, D. Wood, S. Ritchie and S. Cassidy, “Optical wireless: new enabling transmitter technologies,” IEEE International Conference on Communications, vol. 1, pp. 562-566, 1993.
[3] T. Ohtsuki, “Multiple subcarrier modulation in optical wireless communications,” IEEE Communications Magazine, vol. 41, no. 3, pp. 74-79, 2003.
[4] J. M. Kahn and J. R. Barry, “Wireless infrared communications,” Proc. of the IEEE, vol. 85, no. 2, pp.265-298, 1997.
[5] L. R. D. Suresh and S. Sundaravadivelu, “Radiation characteristics of photonic antenna for optical wireless communication using beam propagation method,” IEEE International Conference on Signal Processing, Communications and Networking, pp. 294-298, 2007.。
[6] F. Deicke, W. J. Fisher and M. Faulwaber, “Optical wireless communication to eco system,” IEEE Future Network & Mobile Summit, pp.1-8, 2012.
[7] H. H. Refai, J. J. Sluss and H. H. Refai, “The transmission of multiple RF signals in free space optics using wavelength division multiplexing,” Proc. of SPIE, vol. 5793, pp. 136-143, 2005.
[8] D. Wu, Z. Ghassemlooy, H. LeMinh, S. Rajbhandari and Y. S. Kavian, “Power distribution and Q-factor analysis of diffuse cellular indoor visible light communication system,” Proc. of NOC, pp. 28-31, 2011.
[9] C. Y. Lin, Y. P. Lin, H. H. Lu, C. Y. Chen, T. W. Jhang and M. C. Chen, “Optical free-space wavelength-division-multiplexing transport system,” Opt. Lett., vol. 39, no. 2, pp. 315-318, 2014.
[10] D. Zhou, P. G. LoPresti and H. H. Refai, “Enlargement of beam coverage in FSO mobile network,” IEEE J. Lightw. Technol., vol. 29, no. 10, pp. 1583-1589, 2011.
[11] H. Moradi, H. H. Refai, and P. G. LoPresti, “Spatial diversity for fiber-bundled FSO nodes with limited mobility,” IEEE J. Lightw. Technol., vol. 30, no. 1, pp. 175-183, 2012.
[12] H. Moradi, H. H. Refai and P. G. LoPresti, “Switched diversity approach for multi-receiving optical wireless systems,” Appl. opt., vol. 50, no. 29, pp. 5606-5614, 2011.
[13] H. Moradi, H. H. Refai, and P. G. LoPresti, “Selection diversity for wireless optical communications with non-CSI non-coherent optimal detection,” Proc. of IEEE Globecom., pp. 1010-1014, 2010.
[14] 易成林，“自由空間光通信技術的發展現狀與未來趨勢”，現代商貿工業，第9期，第19卷，263-264頁，2007。
[15] 楊國輝，“雷射原理與量測”，第3章，五南圖書公司，台北市，2002。
[16] 曹培熙，“雷射安全措施”，國立臺灣大學物理所碩士論文，2002年，6月。
[17] Goff Hill, “The Cable and Telecommunications Professionals' Reference,” Elsevier Inc., UK, 2008.
[18] H. Liebl, “Applied charged particle optics,” Springer Berlin Heidelberg, New York, 2007.
[19] P. LoPresti, H. Refai and J. Sluss, “Adaptive power and divergence to improve airborne networking and communications,” Proc. of the IEEE 24th Digital Digital Avionics Systems Conference, vol. 1, pp. 1.B.1-1.1-6, 2005.
[20] I. Kim, B. McArthur and E. J. Korevaar, “Comparison of laser beam propagation at 785 nm and 1550 nm in fog and haze for optical wireless communications,” Proc. of the SPIE, vol. 4214, pp. 26–37, 2001.
[21] L. Rayleigh, “On the transmission of light through an atmosphere containing small particles in suspension, and on the origin of the blue of the sky,” Philosophical Magazine, vol. 47, no. 287, pp. 375-384, 1899.
[22] C. F. Bohren and D. Huffman, “Absorption and scattering of light by small particles,” John Wiley, New York, 1983.
[23] H. C. van de Hulst, “Light scattering by small particles,” Dover, New York, 1981.
[24] K. D. Langer, and J. Grubor,” Recent developments in optical wireless communications using infrared and visible light,” IEEE of the 9th International Conference on Transparent Optical Networks, vol. 3, pp. 146-157, 2007.
[25] Z. Ghassemlooy, W. Popoola and S. Rajbhandari, “Optical Wireless Communications: System and Channel Modelling with MATLABR,” CRC Press, Taylor& Francis Group, New York, 2012.
[26] C. N. Chen and J. C. Palais, “光纖通信與應用”，新文京開發出版股份有限公司，新北市，2004。
[27] K. Cui, G. Chen, Z. Xu and R. D. Roberts, “Line of sight visible light communication system design and demonstration,”IEEE of the 7th International Symposium on Communication Systems Networks and Digital Signal Processing, pp. 621-625, 2010.
[28] R. Ramaswami and K. N. Sivarajan, “Optical Network,” Morgan Kaufmann, USA, pp. 258-263, 2002.
[29] D. Derickson, “Fiber Optics test and Measurement,” 1st, Prentice Hall, New Jersey, 1998.
[30] S. Haykin, “Communications systems,” 4th, John Wiley & sons, Inc, USA, 2001.
[31] W. Freude, R. Schmogrow, B. Nebendah, M. Winter, A. Josten, D. Hillerkuss, S. Koenig, J. Meyer, M. Dreschmann, M. Huebner, C. Koos, J. Becker, J. Leuthold, “Quality metrics for optical signals: eye diagram, Q-factor, OSNR, EVM and BER,” IEEE 14th International Conference on Transparent Optical Networks, pp. 1-4, 2012.
[32] W. S. Tsai, H. H. Lu, S. H. Chen, T. S. Chien, W. N. Chen and M. H. Tu, “Improvement of IEEE 802.11a systems over radio on multimode fiber applications,” IEEE Photon. Technol. Lett., vol. 17, no. 10, pp. 2230-2232, 2005.
[33] R. Hui and M. O'Sullivan. “Fiber Optic Measurement Techniques,” Elsevier Inc, USA, 2009.
[34] 葉嘉哲，“高速雙向無線光通訊參數設計與改良”，國立臺灣科技大學碩士論文，2013，7月。
[35] 林育民，“高容量無線光通訊用於接取網路與橋梁被用路由之設計研究”，國立臺灣科技大學碩士論文，2014，7月。
[36] G. Keiser, “Optical fiber communications,” 5th, Tata McGraw-Hill Education Pvt. Ltd., India, 2013.
[37] 王祥，”線性型單縱模光纖雷射研製” 國立臺灣科技大學碩士論文，2010，1月。
[38] 許偉貞，”波長可調近單縱模線性型光纖雷射” 國立臺灣科技大學碩士論文，2011，7月。
[39] F. Lie’geois, Y. Hernandez, G. Peigne’, F. Roy and D. Hamoir, ”High-efficiency, single longitudinal mode ring fiber laser,” Electron. Lett., vol. 41, no. 13, pp. 729-730, 2005.
[40] C. C. Lee, Y. K. Chen and S. K. Liaw, “Single-longitudinal-mode fiber laser with a passive multiple-ring cavity and its application for video transmission,” Opt. Lett., vol. 23, no. 5, pp. 417-418, 1998.
[41] S. Pan, X. Zhao and C. Lou, “Switchable single-longitudinal-mode dualwavelength erbium-doped fiber ring laser incorporating a semiconductor optical amplifier,” Opt. Lett., vol. 33, no. 8, pp. 764-766, 2008.
[42] J. Liu, J. Yao, J. Yao and T. H. Yeap, “Single-longitudinal-mode multiwavelength fiber ring laser,” IEEE Photon. Technol. Lett., vol. 16, no. 4, pp. 1020-1022, 2004.
[43] 張守進，劉醇星，姬梁文， “半導體雷射” ，科學發展，349期，14-21頁，2002。
[44] 董德國，陳萬清譯，“光纖通訊”，東華圖書股份有限公司，台北市，2000。
[45] R. E. Epworth, “The phenomenon of modal noise in analogue and digital optical fibre systems,” Proc. of 4th European Conference Optical Communication, pp. 492-501, 1978.
[46] A. M. J. Koonen, “Bit-error-rate degradation in a multimode fiber optic transmission link due to modal noise” IEEE J. select. Areas Commun., vol. SAC-4, no. 9, pp.1515-1522, 1986.
[47] 李揚漢、許立根、譚昌文、洪鴻文、曹士林、楊淳良、趙亮琳，“光纖通訊網路”，五南圖書出版股份有限公司，台北市，2007。
[48] 吳軍銳，“基於RGB LED之500Mb/s 高速可見光通訊系統之研究”，國立臺灣科技大學碩士論文，2014，10月。
[49] T. Y. Elganimi, “Performance comparison between OOK, PPM and PAM modulation schemes for free space optical (FSO) communication systems: analytical study,” Int. J. Comput. Appl., vol. 79, no. 11, pp. 22-27, 2013.