本文以具偏光特性之白光發光二極體光源為目標進行各項相關研究，我們選用紫外光晶粒激發螢光粉的方式製作白光發光二極體，其優點為顏色不會隨溫度飄移且演色性高，但缺點為發光效率不高、紫外光外逸。而LED所產生的是非偏極性光，容易造成眩光，使得在應用上有諸多缺點，如應用在室內照明會造成人體感覺不適、在車用照明會造成行車危險等。綜合上述，為了讓白光LED在應用上能夠更具優勢，本文提出一複合光學結構包含「全方位反射器」及「鋁次波長金屬光柵」。全方位反射器可以防止紫外光外漏，並提升LED的發光效率。鋁次波長金屬光柵則用於將具多波長之非偏極性白光轉換成具偏極性白光。
設計製作上，全方位反射器沿用先前研究製作之成品，而鋁次波長金屬光柵透過理論計算找出較佳繞射效率且具可行性之結構參數，接著使用雷射全像顯影術配合反應性離子蝕刻法去製作，所製作出光柵的規格為週期350 nm、厚度為50 nm、空間比為50%，其在可見光波段消光比為1.5。
而將複合光學元件用以封裝白光發光二極體，並以田口式發法調配螢光粉配方，於20 mA的電流驅動下，可得色座標為(0.316, 0.337)、色溫6263 K、演色性96.27，其光源規格已與CIE D65標準光源相當接近。透過頻譜能量強度之量測，全方位反射器能有效阻擋紫外光，且在不傷害電性下增加發光效率32%以上。而鋁次波長金屬光柵可以偏極出射之白光，其消光比為1.52，但會使發光效率降低14%。

This thesis developed a method to generate polarized white light based on exciting multicolor phosphors by ultraviolet (UV) light emitting diode. The advantages of using UV LED generated white light are high color rendering index and wider emission spectrum and the drawbacks are UV leaking and low luminous efficacy.
There are some disadvantages would emerge when LED using in some applications due to LED generate unpolarized light. In interior lighting, glare may cause people uncomfortable. In automobile lighting, glare may increase chance of car accident. For improving these problems, we developed a compound optical element (COE) which combined omni-directional reflector (ODR) with aluminum (Al) subwavelength gratings. Packaged with COE, ODR can solved UV leaking issue and enhance the luminous efficacy. Al gratings can polarize the light passing through it.
In fabrication, ODR had fabricated in previous research. We calculated the parameters of Al subwavelength gratings for achieving better diffraction efficiency in feasible condition. Then, we fabricated Al gratings by laser interference lithography and Reactive Ion Etching. The parameters of the grating, period, thickness, duty ratio, extinction ratio were 350 nm , 50 nm , 50% , 1.5 , respectively.
To packaged white light LED with COE and controlled the composition and concentration of phosphors blend layer by means of Taguchi Method. At a constant applied current of 20 mA, the chromaticity color coordinates, correlated color temperature(CCT), Ra were (0.316, 0.337) , 6263 K and 96.27, respectively. The results were close to that of CIE standard D65 illumination. To measured the spectrum intensity, the ODR packaging structure could enhance the average luminous intensity 32% without any damage on the electronic properties of LED. The Al grating could polarize the white light, the extinction ratio was 1.52,but that would decrease the average luminous intensity 14 %.

[1]R. Zheng, "Luminous Efficiency and Color Rendering of Phosphor- Converted White LEDs," Journal of Light & Visual Environment, vol. 32, pp. 230-233, 2008.
[2]H. Kawamoto, "The history of liquid-crystal displays," Proceedings of the IEEE, vol. 90, pp. 460-500, 2002.
[3]J. A. Wheatley, G. J. Benoit, J. E. Anderson, R. W. Biernath, D. G. Freier, T. R. Hoffend, C. D. Hoyle, T. T. Liu, J. D. Lu, M. A. Meis, V. V. Savvateev, C. R. Schardt, M. E. Sousa, M. F. Weber, and T. J. Nevitt, "Efficient LED light distribution cavities using low loss, angle-selective interference transflectors," Opt. Express, vol. 17, pp. 10612-10622, 2009.
[4]MINANO, J. C., BENITEZ, Pablo, CHAVES, Julio, HEMANDEZ, Maikel, DROSS, Oliver, SANTAMARIA, and Asuncion, High-efficiency LED backlight optics designed with the flow-line method vol. 5942. Bellingham, WA, ETATS-UNIS: Society of Photo-Optical Instrumentation Engineers, 2005.
[5]T. Kasahara, D. Aizawa, T. Irikura, T. Moriyama, M. Toda, and M. Iwamoto, "Discomfort glare caused by white LED light sources," Proceeding of Annual Conference of The Illuminating Engineering Institute of Japan, vol. 38, p. 171 2005.
[6]Schanda.J, "Physical and Visual Requirements for LEDs to be used for Future Lighting system," in Proc., CIE Symposium '04 on LED Light Sources: Physical Physical Measurement and Visual and Photobiological Assessment, Tokyo Japan, 2004, pp. 1-7.
[7]W. Pohlmann, T. Vieregge, and M. Rode, "High performance LED lamps for the automobile: needs and opportunities," in Manufacturing LEDs for Lighting and Displays, Berlin, Germany, 2007, pp. 67970D-15.
[8]J. A. L. E. Wheatley, MN, US), Leatherdale, Catherine A. (St. Paul, MN, US), Ouderkirk, Andrew J. (Woodbury, MN, US), "Polarized LED," US Patent 20060091412, 2006.
[9]S.-n. H.-C. C. Chen, TW), "Light Emitting Diode Illumination Device Capable of Providing Uniformly Polarized Light," US Patent 20090103310, 2009.
[10]S.-c. J. C. Chung, TW), Lin, Chun-chuan (Hsinchu City, TW), Lo, Hsin-hsiang (Jhudong Township, TW), Chen, Tian-yuan (Hsinchu City, TW), Fan, Chih-hsun (Hsinchu City, TW), "Polarized light illumination device," US Patent 20090168393: INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE (Hsinchu, TW), 2009.
[11]A. R. P. Conner, OR, US), Donnelly, Sean M. (Portland, OR, US), Oehler, Peter R. (Aloha, OR, US), "Polarized, LED-based illumination source," US Patent 20060262514, 2006.
[12]A. J. W. Ouderkirk, MN, US), Weber, Michael F. (Shoreview, MN, US), "Phosphor based light sources having a reflective polarizer," US Patent 7091661: 3M Innovative Properties Company (St. Paul, MN, US), 2006.
[13]C.-y. T. C. Huang, TW), Chu, Cheng-wei (Taipei Hsien, TW), "POLARIZED LIGHT EMITTING DEVICE," US Patent 20070064407: INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE (No. 195, Section 4, Chung Hsing Road, Chutung, Hsinchu, TW), 2007.
[14]P. Schlotter, R. Schmidt, and J. Schneider, "Luminescence conversion of blue light emitting diodes," Applied Physics A: Materials Science & Processing, vol. 64, pp. 417-418, 1997.
[15]P. Schlotter, J. Baur, C. Hielscher, M. Kunzer, H. Obloh, R. Schmidt, and J. Schneider, "Fabrication and characterization of GaN/InGaN/AlGaN double heterostructure LEDs and their application in luminescence conversion LEDs," Materials Science and Engineering B, vol. 59, pp. 390-394, 1999.
[16]G. O. Mueller and R. Mueller-Mach, "Illumination-grade white LEDs," in Solid State Lighting II, Seattle, WA, United States, 2002, pp. 122-130.
[17]C.-C. Yang, C.-M. Lin, Y.-J. Chen, Y.-T. Wu, S.-R. Chuang, R.-S. Liu, and S.-F. Hu, "Highly stable three-band white light from an InGaN-based blue light-emitting diode chip precoated with (oxy)nitride green/red phosphors," Applied Physics Letters, vol. 90, pp. 123503-3, 2007.
[18]R. Mueller-Mach, G. Mueller, M. R. Krames, H. A. Hoope, F. Stadler, W. Schnick, T. Juestel, and P. Schmidt, "Highly efficient all-nitride phosphor-converted white light emitting diode," physica status solidi (a), vol. 202, pp. 1727-1732, 2005.
[19]Z. Z. Chen, J. Zhao, Z. X. Qin, X. D. Hu, T. J. Yu, Y. Z. Tong, Z. J. Yang, X. Y. Zhou, G. Q. Yao, B. Zhang, and G. Y. Zhang, "Study on the stability of the high-brightness white LED," physica status solidi (b), vol. 241, pp. 2664-2667, 2004.
[20]T. Nishida, T. Ban, and N. Kobayashi, "High-color-rendering light sources consisting of a 350-nm ultraviolet light-emitting diode and three-basal-color phosphors," Applied Physics Letters, vol. 82, pp. 3817-3819, 2003.
[21]TAKAHASHI, Kohsei, HIROSAKI, Naoto, XIE, Rong-Jun, HARADA, Masamichi, YOSHIMURA, Ken-Ichi, TOMOMURA, and Yoshitaka, Luminescence properties of blue La1-xCexAl(Si6-zAlz ) (N10-zOz) (z~1) oxynitride phosphors and their application in white light-emitting diode vol. 91. Melville, NY, ETATS-UNIS: American Institute of Physics, 2007.
[22]Y. Narukawa, J. Narita, T. Sakamoto, T. Yamada, H. Narimatsu, M. Sano, and T. Mukai, "Recent progress of high efficiency white LEDs," physica status solidi (a), vol. 204, pp. 2087-2093, 2007.
[23]Y.Fink, J.N.Winn, S. Fan, C. Chen, J.Michel, J.D.Joannopoulos, and E. L. Thomas, "A Dielectric Omnidirectional Reflector," Science, vol. 282, p. 1679~1682, 27 Nov 1988.
[24]S. D. Hart, G. R. Maskaly, B. Temelkuran, P. H. Prideaux, J. D. Joannopoulos, and Y. Fink, "External Reflection from Omnidirectional Dielectric Mirror Fibers," Science, vol. 296, pp. 510-513, April 19, 2002 2002.
[25]M. Ibanescu, Y. Fink, S. Fan, E. L. Thomas, and J. D. Joannopoulos, "An All-Dielectric Coaxial Waveguide," Science, vol. 289, pp. 415-419, July 21, 2000 2000.
[26]R. DeCorby, H. Nguyen, P. Dwivedi, and T. Clement, "Planar omnidirectional reflectors in chalcogenide glass and polymer," Opt. Express, vol. 13, pp. 6228-6233, 2005.
[27]E.Hecht and A. Zajac, "section 8.3.1," in Optics: Addidion-Wesley, 1974.
[28]N. Jun and K. Fumio, "Nanofabrication of Sub-Wavelength Grating Using Ultra-Fine Nano-Machining Process," in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies, 2008, p. JTuA34.
[29]S.-W. AHN, K.-D. LEE, J.-S. KIM, S. H. KIM, PARK, Joo-Do, Sarng-Hoon, YOON, and Phil-Won, Fabrication of a 50 nm half-pitch wire grid polarizer using nanoimprint lithography vol. 16. Bristol, ROYAUME-UNI: Institute of Physics, 2005.
[30]呂俊霖, "具有全方位反射器封裝之色溫可調式白光發光二極體," in 光電工程研究所: 國立台灣科技大學, 2008.
[31]"A Guide to Intergrating Sphere Theory and Applications," http://www.labsphere.com/data/userFiles/A%20Guide%20to%20Integrating%20Sphere%20Theory&Apps.pdf, p. 19.
[32]陳仙瑋, "高演色性白光發光二極體封裝," in 光電工程研究所: 國立台灣科技大學, 2007.
[33]S. Nayama and K. Itoh, "Case Study on Combination of Fluorescent Materials for White LED to Obtain High Color Rendering Indexes," Journal of Light & Visual Environment, vol. 30, pp. 39-42, 2006.
[34]G. O. S. J. Mueller, CA, US), Mueller-mach, Regina B. (San Jose, CA, US), Bertram, Dietrich (Aachen, DE), Juestel, Thomas (Aachen, DE), Schmidt, Peter J. (Aachen, DE), Opitz, Joachim (Aachen, DE), "Light-emitting devices utilizing nanoparticles," United States, 2005.
[35]陳文彥, "白光發光二極體封裝研究," in 電子工程所: 國立台灣科技大學, 2007.
[36]"GSOLVER," http://www.gsolver.com.
[37]L. Rayleigh, "On the Dynamical Theory of Gratings," Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, vol. 79, pp. 399-416, 1907.
[38]M. Honkanen, V. Kettunen, M. Kuittinen, J. Lautanen, J. Turunen, B. Schnabel, and F. Wyrowski, "Inverse metal-stripe polarizers," Applied Physics B: Lasers and Optics, vol. 68, pp. 81-85, 1999.
[39]G. Cincotti, "Polarization gratings: design and applications," Quantum Electronics, IEEE Journal of, vol. 39, pp. 1645-1652, 2003.
[40]Z. e. Bomzon, V. Kleiner, and E. Hasman, "Space-variant polarization state manipulation with computer-generated subwavelength metal stripe gratings," Optics Communications, vol. 192, pp. 169-181, 2001.
[41]E. Hasman, Z. e. Bomzon, A. Niv, G. Biener, and V. Kleiner, "Polarization beam-splitters and optical switches based on space-variant computer-generated subwavelength quasi-periodic structures," Optics Communications, vol. 209, pp. 45-54, 2002.
[42]T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature, vol. 391, pp. 667-669, 1998.
[43]D. L. Brundrett, E. N. Glytsis, and T. K. Gaylord, "Homogeneous layer models for high-spatial-frequency dielectric surface-relief gratings: conical diffraction and antireflection designs," Appl. Opt., vol. 33, pp. 2695-2706, 1994.
[44]D. H. Raguin and G. M. Morris, "Antireflection structured surfaces for the infrared spectral region," Appl. Opt., vol. 32, pp. 1154-1167, 1993.
[45]D. L. Brundrett, E. N. Glytsis, and T. K. Gaylord, "Subwavelength transmission grating retarders for use at 10.6 ?m," Appl. Opt., vol. 35, pp.6195-6202, 1996.
[46]E. N. Glytsis, "Two-dimensionally-periodic diffractive optical elements: limitations of scalar analysis," J. Opt. Soc. Am. A, vol. 19, pp.702- 715, 2002.
[47]M. G. Moharam and T. K. Gaylord, "Rigorous coupled-wave analysis of planar-grating diffraction," J. Opt. Soc. Am., vol. 71, pp. 811-818,1981.
[48]L. Poladian, "Simple grating synthesis algorithm," Opt. Lett., vol. 25, pp. 787-789, 2000.
[49]M. G. Moharam, D. A. Pommet, E. B. Grann, and T. K. Gaylord, "Stable implementation of the rigorous coupled-wave analysis for surface-relief gratings: enhanced transmittance matrix approach," J. Opt. Soc. Am. A, vol. 12, pp. 1077-1086, 1995.
[50]B. W. Shore, M. D. Perry, J. A. Britten, R. D. Boyd, M. D. Feit, H. T. Nguyen, R. Chow, G. E. Loomis, and L. Li, "Design of high-efficiency dielectric reflection gratings," J. Opt. Soc. Am. A, vol. 14, pp. 1124-1136, 1997.
[51]D. Palik, "Handbook of Optical Constants of Solids," Academic Press, 1985, p. 275.
[52]D. Kim and K. Burke, "Design of a Grating-Based Thin-Film Filter for Broadband Spectropolarimetry," Appl. Opt., vol. 42, pp. 6321-6326,2003.
[53]E. Popov and S. Enoch, "Mystery of the double limit in homogenization of finitely or perfectly conducting periodic structures," Opt. Lett., vol. 32, pp. 3441-3443, 2007.
[54]C. R. Paul, Introduction to Electromagnetic Compatibility: Wiley-Interscience, 1992.