1. Perfectly vertical surface grating couplers using subwavelength engineering for increased feature sizes
- Author
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Dan-Xia Xu, Mohsen Kamandar Dezfouli, Alejandro Sánchez-Postigo, G. Wanguemert-Perez, Pavel Cheben, Siegfried Janz, Jens H. Schmid, Daniele Melati, Ross Cheriton, Alejandro Ortega-Moñux, and Yuri Grinberg
- Subjects
Fabrication ,Materials science ,business.industry ,Bandwidth (signal processing) ,Metamaterial ,diffraction gratings ,grating couplers ,02 engineering and technology ,coupling efficiency ,Grating ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010309 optics ,Optics ,effective medium theory ,0103 physical sciences ,Broadband ,subwavelength gratings ,space division multiplexing ,0210 nano-technology ,business ,Surface grating ,Refractive index ,Diffraction grating - Abstract
We present perfectly vertical grating couplers for the 220 nm silicon-on-insulator platform incorporating subwavelength metamaterials to increase the minimum feature sizes and achieve broadband low back-reflection. Our study reveals that devices with high coupling efficiencies are distributed over a wide region of the design space with varied back-reflections, while still maintaining minimum feature sizes larger than 100 nm and even 130 nm. Using 3D-finite-difference time-domain simulations, we demonstrate devices with broadband low back-reflection of less than − 20 d B over more than 100 nm bandwidth centered around the C-band. Coupling efficiencies of 72% and 67% are achieved for minimum feature sizes of 106 nm and 130 nm, respectively. These gratings are also more fabrication tolerant compared to similar designs not using metamaterials.
- Published
- 2020