本論文研究主要探討次波長光柵耦合器如何在入射光垂直入射耦合的情況下，降低穿透至基板的繞射光並維持高效率耦合，本研究所使用的模擬方法為有限時域差分法(Finite-Difference Time-Domain ; FDTD)，對於光柵週期、薄膜厚度、不同光柵結構、反射光柵的加入與布拉格反射鏡影響耦合效率做詳細的探討。
模擬上光源的為中心波長為1310 nm的高斯光束，波導材料選用為〖Ta〗_2 O_5，包覆層材料為〖SiO〗_2。模擬結果顯示結合布拉格反射鏡與反射光柵下最佳垂直耦合效率。並發現光柵週期的倍數亦可將光耦入波導。
製程上以電子束微影(Electron-beam lithography)製作光阻光柵於波導層上，並選用直接於光阻光柵上鍍製一層〖Ta〗_2 O_5包覆之製作耦合光柵，為一種可使光柵形貌與蝕刻製程相近之製程。
最後量測上，在利用單模光纖作為光源，強度為20mW的情況下，成功的將波長1310 nm的紅外光耦合進波導並耦合出，並量測到耦出光強為約35.3μW。

The purpose in this study is the design and fabrication of a sub-wavelength grating coupler with high efficiency for vertical coupling.We designed the coupler using the Finite-Difference Time-Domain (FDTD) method. The grating period, film thickness, different grating structure, reflector grating and distributed Bragg reflector were discussed to enhance the coupling efficiency in detail.
The light source is a Gaussian beam with the central wavelength, 1310 nm. The waveguide layer and cladding layer materials are 〖Ta〗_2 O_5 and 〖SiO〗_2, respectively. The highest coupling efficiency 63% with reflector grating and distributed bragg reflector at wavelength 1310 nm was achieved by our simulation. The multiple grating period also has a high coupling efficiency.
In experimental, we used electron-beam lithography to fabricate the sub-wavelength photoresist grating on a 〖Ta〗_2 O_5 waveguide layer. Then a 〖Ta〗_2 O_5 layer was deposited on the photoresist grating to form the coupler grating.
Finally, a single-mode fibers light source with the intensity of 20mW was used to measure the sub-wavelength grating. The intensity of the out coupling light on the coupler grating is 35.3μW .

1. Miller, S.E. ,Integrated Optics:An Introduction. Bell System Technical Journal, 1969. 48(7): p. 2059-2069.
2. 陳彥良, 平面波導光柵耦合生物感測器, 機械工程學系. 2010, 中正大學.
3. J. Dostalek and J. Homola, Surface plasmon resonance sensor based on an array of diffraction gratings for highly parallelized observation of biomolecular interactions, Sensors and Actuators B-Chemical, 2008, vol. 129, p. 303-310.
4. A. L. Weikel, S. D. Conklin, and J. N. Richardson, "A multiple reflection attenuated total reflectance sensor incorporating a glass-indium tin oxide surface modified via direct attachment or film encapsulation of colloidal gold nanoparticles," Sensors and Actuators B-Chemical, 2005, vol. 110, p. 112-119.
5. J. J. Hu, V. Tarasov, A. Agarwal, L. Kimerling, N. Carlie, L. Petit, and K. Richardson, "Fabrication and testing of planar chalcogenide waveguide integrated microfluidic sensor," Optics Express, 2007, vol. 15, p. 2307-2314.
6. M. Li, L. Chen, S. Y. Chou, Direct three-dimensional patterning using nanoimprint lithography, 2001, Appl. Phys. Lett. 78, 3322.
7. S. Y. Chou, P. R. Krauss, P. J. Renstrom, Imprint Lithography with 25-Nanometer Resolution, 1996, Science 272, 85.
8. P. K. Tien, R. Ulrich, R. J. Martin, Modes of Propagating Light Waves In Thin Deposited Semiconductor Films. Applied Physics Letters. 1969. 14(9), p.291-294
9. R. Ulrich, Efficiency of optical-grating couplers. Journal of the Optical Society of America, 1973. 63(11), p1419-1431.
10. M. L. Dakss, L. Kuhn , P. F. Heidrich, B. A. Scott, Grating coupler for efficient excitation of optical guided waves in the thin films. Applied Physics Letters, 1970. 16(12): p. 523-525
11. Bin Wang, Jianhua Jiang, Gregory P. Nordin, Compact slanted grating couplers, Optical Society of America, 2004. Vol. 12, No. 15.
12. Xia Chen, Chao Li, Hon Ki Tsang. Fabrication-Tolerant Waveguide Chirped Grating Coupler for Coupling to a Perfectly Vertical Optical Fiber. IEEE Photonics Technology Letters, 2009. 20(23), 1914-1916.
13. Junbo Yang, Zhiping Zhou, Xueao Zhang, Qin Shiqiao, High-performance and compact binary blazed grating coupler based on an asymmetric subgrating structure and vertical coupling. 2011. 10.1364/OL.36.002614.
14. 張佑誠, 於平面波導上製作次波長光柵耦合結構之研究, 光電科學與工程學系. 2015, 中央大學.
15. 楊彪, 李智勇, 肖希, Nemkova Anastasia, 余金中, 俞育德 硅基光柵耦合器的研究進展, 2013 光子學報, 184214.
16. Dirk Taillaer, Harold Chong, Peter I. Borel, Lars H. Frandsen, Richard M. De La Rue, Roel Baets, A Compact Two-Dimensional Grating Coupler Used as a Polarization Splitter. 2003. IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 15, NO. 9, 1249-1251.
17. Bin Wang, Jianhua Jiang, Gregory P. Nordin, IEEE PHOTONICS TECHNOLOGY LETTERS, 2005. VOL. 17, NO. 9, 1884-1886.
18. Günther Roelkens, Dries Van Thourhout, Roel Baets. 2007. Optical Society of America, Vol. 32, No. 11 / OPTICS LETTERS, 1495-1497.
19. 林聖富, Application of Aptasensor by Using Guided Mode Resonance for Thrombin Detection, 光電科學與工程學系, 2009, 中央大學.p.17-27.
20. Cottier, K., Advanced Label-free Biochemical Sensors Based on Integrated optical waveguide Grating, Insititut of Microtechnique. 2004, Neuchatel.
21. K. S. Yee, Numerical solution of initial boundary value problems involving Maxwell’s equation in isotropic media. IEEE Transactions Antennas and Propagation, 1996. 14: p.302-307
22. J. D. Joannopoulos, R. D. Meade, and J. N. Winn, Princeton University Press(1995).
23. 盧贊文, 李柏璁, 光通訊波長二維光子晶體雷射發展簡介.
24. 李正中, 薄膜光學與鍍膜技術, 第七版.2002藝軒圖書.
25. Dingshan Gao, Zhiping Zhou, Nonlinear equation method for band structure calculations of photonic crystal slabs. Applied Physics Letters, 2006, 88. 163105-163-3
26. 武華, 郭霞, 韓明夫. Design of high efficiency grating coupler for vertical coupling. ACTA PHOTONICA SINICA. 2013, 1004-4213(2013)07-0777-5
27. M. J. Chuang, K. Y. Hsieh, A. K. Chu, High-Temperature Wet Chemical Etching of Ta_2 O_5 in NaOH-Based Solutions for Fabricating Antiresonant Reflecting Optical Waveguides. J. Electrochem. Soc.,1998. 145, No.3.
28. 黃文雄, 製程參數對薄膜應力影響之研究, 光電科學所. 2001, 中央大學.
29. 機台介紹, 國立中央大學光電科學研究中心網站.
30. 李其紘, 原子力顯微鏡的基本介紹, 2013, 科學研習, No.52-5.
31. Manifacier, J. C. , J. Gasiot, and J.P. Fillard, A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film. Journal of Physics E: Scientific Instruments, 1976. 9(11): p. 1002
32. Miura, K. ,Y. Ohtera, H. Ohkubo, T. Sato, N. Akutsu, M. Hikage, N. Ishino, T. Kawashima, and S. Kawakami, Loss reduction of photonic crystal waveguide fabricated by the autocloning technology. Electronics and Communications in Japan (Part Ⅱ: Elactronics), 2005. 88(11): p. 10-20.