Design of a barcode-like waveguide nanostructurefor efficient chip–fiber coupling
A barcode-like waveguide nanostructure with discretized multilevel pixel lines is designed and optimized by a nonlinear search algorithm. We obtain the design of a one-dimensional multilevel nanostructure with ?1.04 dB efficiency for surface normal coupling to a standard single-mode fiber. Another design is achieved from the automatic optimization process, which enables polarization-independent coupling to a single-mode fiber. The optimum coupling efficiency is simulated to be ?2.83 dB for TE and ?3.49 for TM polarization centered near the 1550 nm wavelength. Polarization-dependent loss of less than 1 dB over 45.3 nm is achieved.
基金项目：National Natural Science Foundation of China (NSFC) (61505039); Shenzhen Municipal Science and Technology Plan Project (JCYJ20150403161923530).
Ke Xu：Department of Electronic and Information Engineering, Harbin Institute of Technology, Shenzhen Graduate School, The University Town of Shenzhen, Xili, Shenzhen, China
Qinghai Song：Department of Electronic and Information Engineering, Harbin Institute of Technology, Shenzhen Graduate School, The University Town of Shenzhen, Xili, Shenzhen, China
【1】J. Song, X. Luo, X. Tu, L. Jia, Q. Fang, T. Liow, M. Yu, and G. Q. Lo, “Three-dimensional (3D) monolithically integrated photodetector and WDM receiver based on bulk silicon wafer,” Opt. Express 22, 19546–19554 (2014).
【2】K. Xu, L. G. Yang, J. Y. Sung, Y. M. Chen, Z. Z. Cheng, C. W. Chow, C. H. Yeh, and H. K. Tsang, “Compatibility of silicon Mach–Zehnder modulators for advanced modulation formats,” IEEE J. Lightwave Technol. 31, 1170–1177 (2013).
【3】K. Xu, Z. Cheng, C. Y. Wong, and H. K. Tsang, “Tunable integrated variable bit-rate DPSK silicon receiver,” Opt. Lett. 37, 4738–4740 (2012).
【4】V. R. Almeida, R. R. Panepucci, and M. Lipson, “Nanotaper for compact mode conversion,” Opt. Lett. 28, 1302–1304 (2003).
【5】G. Ren, S. Chen, Y. Cheng, and Y. Zhai, “Study on inverse taper based mode transformer for low loss coupling between silicon wire waveguide and lensed fiber,” Opt. Commun. 284, 4782–4788 (2010).
【6】P. Cheben, J. H. Schmid, S. Wang, D.-X. Xu, M. Vachon, S. Janz, J. Lapointe, Y. Painchaud, and M. J. Picard, “Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency,” Opt. Express 23, 22553–22563 (2015).
【7】F. V. Laere, T. Claes, J. Schrauwen, S. Scheerlinck, W. Bogaerts, D. Taillaert, L. O. Faolain, D. V. Thourhout, and R. Baets, “Compact focusing grating couplers for silicon-on-insulator integrated circuits,” IEEE Photon. Technol. Lett. 19, 1919–1921 (2007).
【8】X. Chen, C. Li, C. K. Y. Fung, S. M. G. Lo, and H. K. Tsang, “Apodized waveguide grating couplers for efficient coupling to optical fibers,” IEEE Photon. Technol. Lett. 22, 1156–1158 (2010).
【9】Z. Cheng, X. Chen, C. Y. Wong, K. Xu, and H. K. Tsang, “Broadband focusing grating couplers for suspended-membrane waveguides,” Opt. Lett. 37, 5181–5183 (2012).
【10】B. Wang, J. H. Jiang, and G. P. Nordin, “Embedded slanted grating for vertical coupling between fibers and silicon-on-insulator planar waveguides,” IEEE Photon. Technol. Lett. 17, 1884–1886 (2005).
【11】X. Chen, C. Li, and H. K. Tsang, “Fabrication-tolerant waveguide chirped grating coupler for coupling to a perfectly vertical optical fiber,” IEEE Photon. Technol. Lett. 20, 1914–1916 (2008).
【12】J. Covey and R. T. Chen, “Efficient perfectly vertical fiber-to-chip grating coupler for silicon horizontal multiple slot waveguides,” Opt. Express 21, 10886–10896 (2013).
【13】A. Y. Piggott, J. Lu, T. M. Babinec, K. G. Lagoudakis, J. Petykiewicz, and J. Vuckovic, “Inverse design and implementation of a wavelength demultiplexing grating coupler,” Sci. Rep. 4, 7210 (2014).
【14】X. Chen, C. Li, and H. K. Tsang, “Two dimensional silicon waveguide chirped grating couplers for vertical optical fibers original research article,” Opt. Commun. 283, 2146–2149 (2010).
【15】M. Streshinsky, R. Shi, A. Novack, R. T. P. Cher, A. E. J. Lim, P. G. Q. Luo, T. B. Jones, and M. Hochberg, “A compact biwavelength polarization splitting grating coupler fabricated in a 220 nm SOI platform,” Opt. Express 21, 31019–31028 (2013).
【16】X. Chen and H. K. Tsang, “Polarization-independent grating couplers for silicon-on-insulator nanophotonic waveguides,” Opt. Lett. 36, 796–798 (2011).
【17】Z. Cheng and H. K. Tsang, “Experimental demonstration of polarization-insensitive air-cladding grating couplers for silicon-on-insulator waveguides,” Opt. Lett. 39, 2206–2209 (2014).
【18】B. Shen, P. Wang, R. Polson, and R. Menon, “An integratednanophotonics polarization beamsplitter with 2.4 μm × 2.4 μm footprint,” Nat. Photonics 9, 378–382 (2015).
【19】A. Y. Piggott, J. Lu, K. G. Lagoudakis, J. Petykiewicz, T. M. Babinec, and J. Vuckovic, “Inverse design and demonstration of a compact and broadband on-chip wavelength demultiplexer,” Nat. Photonics 9, 374–377 (2015).
【20】B. Shen, R. Polson, and R. Menon, “Metamaterial-waveguide bends with effective bend radius < λ0/2,” Opt. Lett. 40, 5750–5753 (2015).
【21】B. Shen, P. Wang, R. Polson, and R. Menon, “Ultra-high-efficiency metamaterial polarizer,” Optica 1, 356–360 (2014).
Xiang Wen, Ke Xu, and Qinghai Song, "Design of a barcode-like waveguide nanostructurefor efficient chip–fiber coupling," Photonics Research 4(6), 209-213 (2016)