P. Cheben, R. Halir, J. H. Schmid, H. A. Atwater, and D. R. Smith, Subwavelength integrated photonics, Nature, vol.560, issue.7720, pp.565-572, 2018.

J. Chiles and S. Fathpour, Silicon photonics beyond silicon-on-insulator, J. Opt, vol.19, issue.5, p.53001, 2017.

F. Boeuf, S. Crémer, E. Temporiti, M. Feré, M. Shaw et al., Silicon Photonics R&D and Manufacturing on 300-mm Wafer Platform, IEEE J. Light. Technol, vol.34, issue.2, pp.286-295, 2016.

R. Halir, A. Ortega-moñux, D. Benedikovic, G. Z. Mashanovich, J. G. Wangüemert-pérez et al., Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices, Proc. IEEE, vol.106, issue.12, pp.2144-2157, 2018.

W. Zhou, Z. Cheng, X. Chen, K. Xu, X. Sun et al., Subwavelength engineering in silicon photonic devices, IEEE J. Sel. Top. Quantum Electron, vol.25, issue.3, p.2900113, 2019.

C. Doerr and L. Chen, Silicon Photonics in Optical Coherent Systems, Proc. IEEE, vol.106, issue.12, pp.2291-2301, 2018.

A. Novack, M. Streshinsky, R. Ding, Y. Liu, A. E. Lim et al., Progress in silicon platforms for integrated optics, Nanophotonics, vol.3, issue.4-5, pp.205-214, 2014.

A. Rahim, T. Spuesens, R. Baets, and W. Bogaerts, Open-Access Silicon Photonics: Current Status and Emerging Initiatives, Proc. IEEE, vol.106, issue.12, pp.2313-2330, 2018.

D. Taillaert, W. Bogaerts, P. Bienstman, T. F. Krauss, P. Van-dale et al., An out-of-plane grating coupler for efficient butt-coupling between compact planar waveguides and single-mode fibers, IEEE J. Quantum Electron, vol.38, issue.7, pp.949-955, 2002.

D. Taillaert, P. Bienstman, and R. Baets, Compact efficient broadband grating coupler for silicon-on-insulator waveguides, Opt. Lett, vol.29, issue.23, pp.2749-2751, 2004.

G. Son, S. Han, J. Park, K. Kwon, and K. Yu, High-efficiency broadband light coupling between optical fibers and photonic integrated circuits, Nanophotonics, vol.7, issue.12, pp.1845-1864, 2018.

D. Vermeulen and C. V. Poulton, Optical Interfaces for Silicon Photonic Circuits, Proc. IEEE, vol.106, issue.12, pp.2270-2280, 2018.

R. Marchetti, C. Lacava, L. Carroll, K. Gradkowski, and P. Minzioni, Coupling strategies for silicon photonics integrated chips, Photon. Res, vol.7, issue.2, pp.201-239, 2019.

V. R. Almeida, R. R. Panepucci, and M. Lipson, Nanotaper for compact mode conversion, Opt. Lett, vol.28, issue.15, pp.1302-1304, 2003.

P. Cheben, D. Xu, S. Janz, and A. Densmore, Subwavelength waveguide grating for mode conversion and light coupling in integrated optics, Opt. Express, vol.14, issue.11, pp.4695-4702, 2006.

, OPTICS EXPRESS, vol.27, issue.18, 2019.

P. J. Bock, P. Cheben, J. H. Schmid, J. Lapointe, A. Delâge et al., Subwavelength grating periodic structures in silicon-on-insulator: a new type of microphotonic waveguide, Opt. Express, vol.18, issue.19, pp.20251-20262, 2010.

T. Barwicz, A. Janta-polczynski, M. Khater, Y. Thibodeau, R. Leidy et al., An O-band metamaterial converter interfacing standard optical fibers to silicon nanophotonics waveguides, Optical Fiber Communication Conference, 2015.

P. Cheben, J. H. Schmid, S. Wang, D. Xu, M. Vachon et al., Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency, Opt. Express, vol.23, issue.17, pp.22553-22563, 2015.

M. Papes, P. Cheben, D. Benedikovic, J. H. Schmid, J. Pond et al., Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides, Opt. Express, vol.24, issue.5, pp.5026-5038, 2016.

T. Barwicz, B. Peng, R. Leidy, A. Janta-polczynski, T. Houghton et al., Integrated Metamaterial Interfaces for Self-Aligned Fiber-to-Chip Coupling in Volume Manufacturing, IEEE J. Sel. Top. Quantum Electron, vol.25, issue.3, p.4700313, 2019.

A. Mekis, S. Gloeckner, G. Masini, A. Narasimha, T. Pinguet et al., A gratingcoupler-enabled CMOS photonics platform, IEEE J. Sel. Top. Quantum Electron, vol.17, issue.3, pp.597-608, 2011.

C. Kopp, S. Bernabé, B. B. Bakir, J. Fédéli, R. Orobtchouk et al., Silicon photonic circuits: On-CMOS integration, fiber optical coupling, and packaging, IEEE J. Sel. Top. Quantum Electron, vol.17, issue.3, pp.498-509, 2011.

C. Li, K. S. Chee, J. Tao, H. Zhang, M. Yu et al., Silicon photonics packaging with lateral fiber coupling to apodized grating coupler embedded circuit, Opt. Express, vol.22, issue.20, pp.24235-24240, 2014.

L. Carroll, J. Lee, C. Scarcella, K. Gradkowski, M. Duperron et al., Photonic Packaging: Transforming Silicon Photonic Integrated Circuits into Photonic Devices, Appl. Sci. (Basel), vol.6, issue.12, p.426, 2016.

A. Bozzola, L. Carroll, D. Gerace, I. Cristiani, and L. C. Andreani, Optimising apodized grating couplers in a pure SOI platform to -0.5 dB coupling efficiency, Opt. Express, vol.23, issue.12, pp.16289-16304, 2015.

R. Halir, P. Cheben, S. Janz, D. Xu, I. Molina-fernández et al., Waveguide grating coupler with subwavelength microstructures, Opt. Lett, vol.34, issue.9, pp.1408-1410, 2009.

R. Halir, P. Cheben, J. H. Schmid, R. Ma, D. Bedard et al., Continuously apodized fiber-to-chip surface grating coupler with refractive index engineered subwavelength structure, Opt. Lett, vol.35, pp.3243-3245, 2010.

X. Chen and H. K. Tsang, Nanoholes grating couplers for coupling between silicon-on-insulator waveguides and optical fibers, IEEE Photonics J, vol.1, issue.3, pp.184-190, 2009.

W. Zhou, Z. Cheng, X. Sun, and H. K. Tsang, Tailorable dual-wavelength-band coupling in a transverseelectric-mode focusing subwavelength grating coupler, Opt. Lett, vol.43, issue.12, pp.2985-2988, 2018.

Y. Tong, W. Zhou, and H. K. Tsang, Efficient perfectly vertical grating coupler for multi-core fibers fabricated with 193 nm DUV lithography, Opt. Lett, vol.43, issue.23, pp.5709-5712, 2018.

D. Gostimirovic and W. N. Ye, An Open-Source Artificial Neural Network Model for Polarization-Insensitive Silicon-on-Insulator Subwavelength Grating Couplers, IEEE J. Sel. Top. Quantum Electron, vol.25, issue.3, p.8200205, 2019.

N. Purwaha, A. Atieh, and W. N. Ye, Broadband and polarization flexible SOI grating coupler based on subwavelength gratings with low back reflections, OSA Continuum, vol.2, issue.4, pp.1350-1357, 2019.

R. Marchetti, C. Lacava, A. Khokhar, X. Chen, I. Cristiani et al., High-efficiency grating-couplers: demonstration of a new design strategy, Sci. Rep, vol.7, issue.1, p.16670, 2017.

D. Benedikovic, P. Cheben, J. H. Schmid, D. Xu, J. Lapointe et al., High-efficiency single etch step apodized surface grating coupler using subwavelength structure, Laser Photonics Rev, vol.8, issue.6, pp.93-97, 2014.

Z. Wang, Y. Tang, L. Wosinski, and S. He, Experimental demonstration of a high-efficiency polarization splitter based on a one-dimensional grating with a Bragg reflector underneath, IEEE Photonics Technol. Lett, vol.22, issue.21, pp.1568-1570, 2010.

C. Baudot, D. Dutartre, A. Souhaité, N. Vulliet, A. Jones et al., Low Cost 300 mm double-SOI substrate for low insertion loss 1D & 2D grating couplers, Proceedings of IEEE 11th International on Group IV Photonics (GFP, pp.137-138, 2014.

Y. Ding, C. Peucheret, H. Ou, and K. Yvind, Fully etched apodized grating coupler on the SOI platform with -0.58 dB coupling efficiency, Opt. Lett, vol.39, issue.18, pp.5348-5350, 2014.
URL : https://hal.archives-ouvertes.fr/hal-01061469

W. S. Zaoui, A. Kunze, W. Vogel, M. Berroth, J. Butschke et al., Bridging the gap between optical fibers and silicon photonic integrated circuits, Opt. Express, vol.22, issue.2, pp.1277-1286, 2014.

L. Carroll, D. Gerace, I. Cristiani, and L. C. Andreani, Optimizing polarization-diversity couplers for Siphotonics: reaching the -1dB coupling efficiency threshold, Opt. Express, vol.22, issue.12, pp.14769-14781, 2014.

D. Benedikovic, P. Cheben, J. H. Schmid, D. Xu, B. Lamontagne et al., Subwavelength index engineered surface grating coupler with sub-decibel efficiency for 220-nm silicon-on-insulator waveguides, Opt. Express, vol.23, issue.17, pp.22628-22635, 2015.

G. Roelkens, D. Van-thourhout, and R. Baets, High efficiency Silicon-on-Insulator grating coupler based on a poly-Silicon overlay, Opt. Express, vol.14, issue.24, pp.11622-11630, 2006.

H. Chen and K. Yang, Design of a high-efficiency grating coupler based on a silicon nitride overlay for silicon-on-insulator waveguides, Appl. Opt, vol.49, issue.33, pp.6455-6462, 2010.

D. Vermeulen, S. Selvaraja, P. Verheyen, G. Lepage, W. Bogaerts et al., High-efficiency fiber-to-chip grating couplers realized using an advanced CMOS-compatible siliconon-insulator platform, Opt. Express, vol.18, issue.17, pp.18278-18283, 2010.

S. Yang, Y. Zhang, T. Baehr-jones, and M. Hochberg, High efficiency germanium-assisted grating coupler, Opt. Express, vol.22, issue.25, pp.30607-30612, 2014.

W. S. Sacher, J. C. Mikkelsen, Y. Huang, J. C. Mak, Z. Yong et al., Monolithically Integrated Multilayer Silicon Nitride-on-Silicon Waveguide Platforms for 3-D Photonic Circuits and Devices, Proc. IEEE, vol.106, issue.12, pp.2232-2245, 2018.

M. Dai, L. Ma, Y. Xu, M. Lu, X. Liu et al., Highly efficient and perfectly vertical chip-to-fiber duallayer grating coupler, Opt. Express, vol.23, issue.2, pp.1691-1698, 2015.

M. T. Wade, F. Pavanello, R. Kumar, C. M. Gentry, A. Atabaki et al., 75% efficient wide bandwidth grating couplers in a 45 nm microelectronics CMOS process, IEEE Optical Interconnects Conference, 2015.

J. Notaros, F. Pavanello, M. T. Wade, C. M. Gentry, A. Atabaki et al., Ultra-Efficient CMOS Fiber-to-Chip Grating Couplers, Optical Fiber Communication Conference

L. Su, R. Trivedi, N. V. Sapra, A. Y. Piggott, D. Vercruysse et al., Fully-automated optimization of grating couplers, Opt. Express, vol.26, issue.4, pp.4023-4034, 2018.

A. Michaels and E. Yablonovitch, Inverse design of near unity efficiency perfectly vertical grating couplers, Opt. Express, vol.26, issue.4, pp.4766-4779, 2018.

C. Alonso-ramos, P. Cheben, A. Ortega-moñux, J. H. Schmid, D. Xu et al., Fiber-chip grating coupler based on interleaved trenches with directionality exceeding 95, Opt. Lett, vol.39, issue.18, pp.5351-5354, 2014.

D. Benedikovic, C. Alonso-ramos, P. Cheben, J. H. Schmid, S. Wang et al., Highdirectionality fiber-chip grating coupler with interleaved trenches and subwavelength index-matching structure, Opt. Lett, vol.40, issue.18, pp.4190-4193, 2015.

X. Chen, D. J. Thomson, L. Crudginton, A. Z. Khokhar, and G. T. Reed, Dual-etch apodised grating couplers for efficient fibre-chip coupling near 1310 nm wavelength, Opt. Express, vol.25, issue.15, pp.17864-17871, 2017.

D. Benedikovic, C. Alonso-ramos, D. Pérez-galacho, S. Guerber, V. Vakarin et al., L-shaped fiber-chip grating couplers with high directionality and low reflectivity fabricated with deep-UV lithography, Opt. Lett, vol.42, issue.17, pp.3439-3442, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01800599

T. Watanabe, M. Ayata, U. Koch, Y. Fedoryshyn, and J. Leuthold, Perpendicular Grating Coupler Based on a Blazed Antiback-Reflection Structure, IEEE J. Light. Technol, vol.35, issue.21, pp.4663-4669, 2017.

Y. Chen, R. Halir, Í. Molina-fernández, P. Cheben, and J. He, High-efficiency apodized-imaging chip-fiber grating coupler for silicon nitride waveguides, Opt. Lett, vol.41, issue.21, pp.5059-5062, 2016.

Y. Chen, T. Bucio, A. Z. Khokhar, M. Banakar, K. Grabska et al., Experimental demonstration of an apodized-imaging chip-fiber grating coupler for Si 3 N 4 waveguides, Opt. Lett, vol.42, issue.18, pp.3566-3569, 2017.

. Fdtd-lumerical and . Solutions,

L. Zavargo-peche, A. Ortega-moñux, J. G. Wangüemert-perez, and I. Molina-fernandez, Fourier based combined techniques to design novel sub-wavelength optical integrated devices, Prog. Electromagnetics Res, vol.123, pp.447-465, 2012.

S. M. Rytov, Electromagnetic properties of a finely stratified medium, Sov. Phys, vol.2, pp.466-475, 1956.

D. Oser, D. Pérez-galacho, C. Alonso-ramos, X. L. Roux, S. Tanzilli et al., Subwavelength engineering and asymmetry: two efficient tools for sub-nanometer-bandwidth silicon Bragg filters, Opt. Lett, vol.43, issue.14, pp.3208-3211, 2018.
URL : https://hal.archives-ouvertes.fr/hal-02413503

R. Halir, L. Zavargo-peche, D. Xu, P. Cheben, R. Ma et al., Single etch grating couplers for mass fabrication with DUV lithography, Opt. Quantum Electron, vol.44, pp.521-526, 2012.

M. Passoni, D. Gerace, L. Carroll, and L. C. Andreani, Grating couplers in silicon-on-insulator: The role of photonic guided resonances on lineshape and bandwidth, Appl. Phys. Lett, vol.110, issue.4, p.41107, 2017.