由於絕緣體層上鍍矽晶片(Silicon-on-insulator, SOI)與微電子技術的高度相容性，SOI也逐漸成為平面光路(Planar Lightwave Circuit, PLC)的主要應用平台。然受制於矽材與空氣、二氧化矽之折射率反差過大，SOI平板波導(Slab waveguide)之單模孔徑僅達0.2 μm，造成極嚴重的光纖耦合問題。我們利用脊形波導(Rib waveguide)結構的特性，在特定結構下，可以抑制波導的高階模態產生，可以達到具 10×6 μm2之大孔徑(Large Cross Section)，且經由計算其與單模光纖的直接耦合 (Butt-joint) 效率可高達-1.25 dB，使其易於與光纖連結並增加實用性。
為了使微光學元件在平面光路上達到高密度的整合，波導結構需要在小區域裡達到大角度的彎曲。我們利用相位補償(Phase Compensation)的方式，在彎曲過程中，經由空氣柱微稜鏡讓波導之特徵模態得以維持。對於上述所提之大孔徑的單模脊形波導，我們設計出具有10°的大角度彎曲波導結構，曲率半徑僅達27 μm，且彎曲損耗僅達-1.61 dB。
我們也利用導波共振結構(Guide-mode Resonance, GMR)的特性，將SOI脊形波導與GMR光柵積體化，可以達到濾波器之效果。我們設計了一個單一週期雙填充率之非對稱性光柵結構，作為一強調制之濾波器，可以分離通訊用波長1310 nm與1550 nm之訊號。在PLC上將GMR與脊形波導整合之整體(monolithic)積體化元件，具有相當吸引人的應用價值。

Silicon-on-insulator (SOI) waveguides have received much attention as a platform for planar lightwave circuits (PLCs) due to their compatibility with complementary metal oxide semiconductor (CMOS) technologies. Light in the silicon layer of SOI is naturally confined in the vertical direction because of the high index contrast between the bottom oxide layer, Si layer, and air. However, owing to the inherently large index contrast between si and air, the core size of a single-mode SOI waveguide is generally less than sub-micro size, resulting in a very serious coupling problem.
Rib waveguide with specific structure can provide a core width with large cross-section, but still maintain in single-mode operation. In this paper, a large single-mode rib waveguide is designed and demonstrated. For easily coupling to SMF, the upper silicon layer is chosen to 10 μm, and the corresponding width of core is 6 μm with etching depth equal to 3.5 μm. On the basis of the above design, a calculation results of a butt-joint interconnect from SMF can be as high as -1.25 dB. The polarization-dependence loss is less than 0.01 dB, and wavelength- dependent loss preserves 1 dB variation within 100 nm.
For the purpose of high-density integration in PLC, a phase- compensated air-based microprism is introduced to a wide-angle bending rib waveguide. An air microprism, which can be made by directly dry etching up to oxide layer, compensates the phase difference in this rib waveguide bend, and then properly tilts the planar wavefront to the designed bending angle. A 10° bending waveguide with radius of curvature of only 27.1 μm is designed and fabricated.
In the last section of this paper, a monolithic integration of guide-mode resonance (GMR) filter and rib waveguide is proposed and analyzed. This GMR with structure of grating and waveguide can be directly fabricated by dry-etching process on the top Si layer of SOI. A 1310/1550 nm filter by this monolithic structure is designed. Strong modulation in the grating structure with two-filling factor design can enlarge the operating wavelength window to more than 40 nm, which can avoid general wavelength shift by temperature variation.

[1] R. A. Soref, J. Schmidtchen, and K. Petermann, “Large single-mode rib waveguides in GeSi-Si and Si-on-SiO2,” IEEE J. Quantum Electron., vol. QE-27, pp. 1971-1974, 1986
[2] S. P. Pogossian, L. Vescan, and A. Vonsovici, “The single-mode conditionfor semiconductor rib waveguides with large cross-section,” J.
Lightwave Technol., vol. 16, pp. 1851–1853, 1998
[3] Yurii A. Vlasov and Sharee J. McNab, ‘‘Losses in single-mode silicon-on-insulator strip waveguides and bends,’’ Opt. Express 12, 1622, 2004
[4] K. Solehmainen, and M. Leskela, “Dry-Etched Silicon-on-Insulator Waveguides With Low Propagation and Fiber-Coupling Losses,” J. Lightwave Technol.vol. 23, pp3875-3879, 2005
[5] Y. Qian, S. Kim, and G. P.Nordin, ”Compact and low loss silicon-on-insulator rib waveguide 900 bend,” Optics Express. vol. 14, pp.6020-6028, 2006
[6] Thomas Edward Murphy , Jeffrey Todd Hastings, and Henry I. Smith, “Fabrication and Characterization of Narrow-Band Bragg-Reflection Filters in Silicon-on-Insulator Ridge Waveguides,” J. Lightwave Technol. , pp.1938-1942, 2001
[7] Han-Bin Lin, Jung-Young Su,and Way-Seen Wang,”Design and Application of Very Low-Loss Abrupt Bends in Optical Waveguide,” J. Quantum Electronics,Vol 30, 1994
[8] Han-Bin Lin, Yih-Bin Lin, and Way-Seen Wang,”Analysis of Abrupt Waveguide Bend with Low-Index Microprism,” J. Quantum Electronics,Vol 34., 1998
[9] Ching-Ting Lee, Mount-Learn Wu, ”Apexes-Linked Circle Gratings for Low-Loww Waveguide Bends,” IEEE Photon. Technol. Lett., Vol 13, 2001
[10] J. Lousteau, D. Furniss,A. B. Seddon,T. M. Benson, Senior Member, ”The Single-Mode Condition for Silicon-on-Insulator Optical Rib Waveguide With Large Cross Section,” J. Lightwave Technol.vol. 22,pp.1923-1929, 2004
[11] R. A. Soref, J. Schmidtchen, and K. Petermann, “Large single-moderib waveguides in GeSi-Si and Si-on-SiO2,” IEEE J. QuantumElectron., vol. QE-27, pp. 1971-1974, 1986
[12] W.P. Huang, C.L. Xu, “Simulation of three-dimensional optical waveguides by a full-vector beam propagation method,” IEEE J.
Quantum Electron, Vol. 29, pp. 2639-2649 , 1993
[13] H. B. Lin, J.Y. Su, P. K.Wei, andW. S.Wang, “Design and application of very low-loss bends in optical waveguides,” IEEE J. Quantum Electron., vol. 30, pp. 2827–2835, 1994.
[14] K.S. Yee, “Numerical solution of initial boundary value problems
involving maxwell’s equations in isotropic media,” IEEE Trans.Antennas Propag. , 14, 302, 1966
[15] K. Kawano, “Introduction to Optical Waveguide Analysis:Solving
Maxwell’s Equations and the Schrödinger Equation,” T. Kiton,
, 2001
[16] A.Tavlove, ”The Finite-Difference Time-Domain Method”, Computational Electrodynamics, 1995
[17] J. P. Berenger, “A Perfectly Matched Layer for the Absorption of
Electromagnetic Waves,” J. Comput. Phys. , 114, 185 ,1994
[18] Graham T. Reed ,Andrew P. Knights, ”Silicon Photonics An Introduction,” England, 2004
[19] Che-Lung Hsu, Yung-Chih Liu, Chih-Ming Wang, Mount-Learn Wu, Ya-Lun Tsai, Yue-Hong Chou,Chien-Chieh Lee,and Jenq-Yang Chang , ”Bulk-Micromachined Optical Filer Based on Guided-Mode Resonance in Silicon-Nitride Membrane,” J. Lightwave Technol.vol. 24,pp.1922-1927, 2006
[20] Kaspar F.G. ”Diffraction by thick, periodically stratified grating with complex dielectric constant,” J. Opt. Soc. Am. 63, 37, 1973
[21] Mount-Learn Wu, Che-Lung Hsu, and Yung-Chih Liu, ”Silicon-based and suspended-membrane-type guided-mode resonance filters with a spectrum-modifying layer design,” Optics Letters. vol. 31,pp.3333-3335, 2006
[22] Che-Lung Hsu, Mount-Learn Wu, Yung-Chih Liu,Yun-Chih Lee, and Jenq-Yang Chang, ”Flattened Broadband Notch Filters Using Guided-Mode Resonance Associated With Asymmetric Binary Gratings,” IEEE PHOTONICS TECHNOLOGY LETTERS
vol. 18,pp2572-2574, 2006