Design and Analysis of Optical Coupling Between Silicon Nanophotonic Waveguide and Standard Single-Mode Fiber Using an Integrated Asymmetric Super-GRIN Lens

Author

Wang, Qian ; Loh, Ter-Hoe ; Ng, Doris Keh Ting ; Ho, Seng-Tiong

Author_Institution

Data Storage Inst., Agency for Sci., Technol. & Res. (A*STAR), Singapore, Singapore

Volume

17

Issue

3

fYear

2011

Firstpage

581

Lastpage

589

Abstract

Comprehensive design and analysis of optical coupling between silicon nanophotonic waveguide and standard single-mode fiber is presented. The coupling structure employs an integrated asymmetric graded refractive index (GRIN) lens deposited at the end of the tapered waveguide, and the GRIN lens has an optimized refractive index profile with a super high numerical aperture for aberration-free subwavelength focusing/collimating. The influence of end-facet reflection of the GRIN lens on the coupling efficiency is investigated. The optimized GRIN lens with a proper antireflection coating shows a coupling efficiency of ~90% between a 300-nm-thick silicon nanophotonic waveguide and a standard single-mode fiber. A 3-D modeling and simulation of the GRIN lens is carried out. The influences of fiber displacement and angular misalignment on the coupling efficiency are analyzed. The overall systematic design and analysis indicate that this integrated GRIN-lens-based optical coupler offers a compact and efficient solution for nanophotonic waveguide coupling with a good alignment tolerance.

Keywords

antireflection coatings; elemental semiconductors; gradient index optics; integrated optics; integrated optoelectronics; lenses; nanophotonics; optical design techniques; optical fibre couplers; optical focusing; optical waveguides; optimisation; refractive index; silicon; 3D modeling; Si; aberration-free subwavelength collimation; aberration-free subwavelength focusing; antireflection coating; asymmetric graded refractive index lens; coupling efficiency; end-facet reflection; integrated asymmetric super-GRIN lens; optical coupling; optical design; optimized refractive index profile; silicon nanophotonic waveguide; size 300 nm; standard single-mode fiber; tapered waveguide; Couplings; Lenses; Optical coupling; Optical refraction; Optical variables control; Optical waveguides; Silicon; Fiber coupling; graded refractive index (GRIN) lens; silicon photonics;

fLanguage

English

Journal_Title

Selected Topics in Quantum Electronics, IEEE Journal of

Publisher

ieee

ISSN

1077-260X

Type

jour

DOI

10.1109/JSTQE.2010.2075917

Filename

5669329