Disorder effects in subwavelength grating metamaterial waveguides

Subwavelength grating (SWG) waveguides are integrated photonic structures with a pitch substantially smaller than wavelength for which they are designed, so that diffraction effects are suppressed. SWG operates as an artificial metamaterial with an equivalent refractive index which depends on the geometry of the structure and the polarization of the propagating wave. SWG waveguides have been advantageously used in silicon photonics, resulting in significant performance improvements for many practical devices, including highly efficient fiber-chip couplers, waveguide crossings, broadband multimode interference (MMI) couplers, evanescent field sensors and polarization beam splitters, to name a few. Here we present a theoretical and experimental study of the influence of disorder effects in SWG waveguides. We demonstrate via electromagnetic simulations and experimental measurements that even a comparatively small jitter (~5 nm) in the position and size of the SWG segments may cause a dramatic reduction in the transmittance for wide (multimode) SWG waveguides, while for narrow (single mode) waveguides this effect is negligible. Our study shows that the impact of the jitter on SWG waveguide performance is directly related to the modal confinement. © 2017 Optical Society of America OCIS codes: (130.0130) Integrated optics; (250.5300) Photonic integrated circuits; (130.3120) Integrated optics devices; (050.6624) Subwavelength structures; (160.3918) Metamaterials. References and links 1. S. M. Rytov, “The electromagnetic properties of finely layered medium,” Sov. Phys. JETP 2, 466–475 (1956). 2. M. W. Farn, “Binary gratings with increased efficiency,” Appl. Opt. 31(22), 4453–4458 (1992). 3. P. Cheben, D.-X. Xu, S. Janz, and A. Densmore, “Subwavelength waveguide grating for mode conversion and light coupling in integrated optics,” Opt. Express 14(11), 4695–4702 (2006). 4. P. Cheben, P. J. Bock, J. H. Schmid, J. Lapointe, S. Janz, D. X. Xu, A. Densmore, A. Delâge, B. Lamontagne, and T. J. Hall, “Refractive index engineering with subwavelength gratings for efficient microphotonic couplers and planar waveguide multiplexers,” Opt. Lett. 35(15), 2526–2528 (2010). 5. 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(17), 22553–22563 (2015). 6. D. Benedikovic, P. Cheben, J. H. Schmid, D. X. Xu, B. Lamontagne, S. Wang, J. Lapointe, R. Halir, A. OrtegaMoñux, S. Janz, and M. Dado, “Subwavelength index engineered surface grating coupler with sub-decibel efficiency for 220-nm silicon-on-insulator waveguides,” Opt. Express 23(17), 22628–22635 (2015). 7. D. Benedikovic, C. Alonso-Ramos, P. Cheben, J. H. Schmid, S. Wang, R. Halir, A. Ortega-Moñux, D. X. Xu, L. Vivien, J. Lapointe, S. Janz, and M. Dado, “Single-etch subwavelength engineered fiber-chip grating couplers for 1.3 μm datacom wavelength band,” Opt. Express 24(12), 12893–12904 (2016). 8. X. Xu, H. Subbaraman, J. Covey, D. Kwong, A. Hosseini, and R. T. Chen, “Complementary metal–oxide– semiconductor compatible high efficiency subwavelength grating couplers for silicon integrated photonics,” Appl. Phys. Lett. 101(3), 031109 (2012). 9. A. Sánchez-Postigo, J. Gonzalo Wangüemert-Pérez, J. M. Luque-González, Í. Molina-Fernández, P. Cheben, C. A. Alonso-Ramos, R. Halir, J. H. Schmid, and A. Ortega-Moñux, “Broadband fiber-chip zero-order surface grating coupler with 0.4 dB efficiency,” Opt. Lett. 41(13), 3013–3016 (2016). Vol. 25, No. 11 | 29 May 2017 | OPTICS EXPRESS 12222

[1]  J. Ctyroky,et al.  3-D Bidirectional Propagation Algorithm Based on Fourier Series , 2012, Journal of Lightwave Technology.

[2]  Jinbiao Xiao,et al.  Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler , 2016, Scientific Reports.

[3]  Pavel Cheben,et al.  Evanescent field waveguide sensing with subwavelength grating structures in silicon-on-insulator. , 2014, Optics letters.

[4]  Siegfried Janz,et al.  Refractive index engineering with subwavelength gratings for efficient microphotonic couplers and planar waveguide multiplexers. , 2010, Optics letters.

[5]  P. Cheben,et al.  Subwavelength waveguide grating for mode conversion and light coupling in integrated optics. , 2006, Optics express.

[6]  Siegfried Janz,et al.  Waveguide subwavelength structures : a review of principles and applications , 2014 .

[7]  Lawrence R. Chen.  Subwavelength grating waveguide devices in silicon-on-insulators for integrated microwave photonics (Invited Paper) , 2017 .

[8]  Pavel Cheben,et al.  Polarization splitter and rotator with subwavelength grating for enhanced fabrication tolerance. , 2014, Optics letters.

[9]  Siegfried Janz,et al.  Subwavelength index engineered surface grating coupler with sub-decibel efficiency for 220-nm silicon-on-insulator waveguides. , 2015, Optics express.

[10]  Siegfried Janz,et al.  Subwavelength grating Fourier‐transform interferometer array in silicon‐on‐insulator , 2013 .

[11]  I Molina-Fernández,et al.  Suspended silicon mid-infrared waveguide devices with subwavelength grating metamaterial cladding. , 2016, Optics express.

[12]  Pavel Cheben,et al.  Controlling leakage losses in subwavelength grating silicon metamaterial waveguides. , 2016, Optics letters.

[13]  Daniele Melati,et al.  Real photonic waveguides: guiding light through imperfections , 2014 .

[14]  Ivana Gasulla,et al.  Subwavelength grating enabled on-chip ultra-compact optical true time delay line , 2016, Scientific Reports.

[15]  Siegfried Janz,et al.  Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency. , 2015, Optics express.

[16]  Jens H. Schmid,et al.  Ultra‐broadband nanophotonic beamsplitter using an anisotropic sub‐wavelength metamaterial , 2016 .

[17]  D. Marris-Morini,et al.  Add/Drop Mode-Division Multiplexer Based on a Mach–Zehnder Interferometer and Periodic Waveguides , 2015, IEEE Photonics Journal.

[18]  Shon Schmidt,et al.  Sub-wavelength grating for enhanced ring resonator biosensor. , 2016, Optics express.

[19]  M W Farn,et al.  Binary gratings with increased efficiency. , 1992, Applied optics.

[20]  Siegfried Janz,et al.  Single-etch subwavelength engineered fiber-chip grating couplers for 1.3 µm datacom wavelength band. , 2016, Optics express.

[21]  Fan Zhang,et al.  Broadband 2 × 2 adiabatic 3  dB coupler using silicon-on-insulator sub-wavelength grating waveguides. , 2016, Optics letters.

[22]  Ray T. Chen,et al.  Complementary metal–oxide–semiconductor compatible high efficiency subwavelength grating couplers for silicon integrated photonics , 2012 .

[23]  Zhiping Zhou,et al.  Manipulation of beat length and wavelength dependence of a polarization beam splitter using a subwavelength grating. , 2016, Optics letters.