Silicon-based highly-efficient fiber-to-waveguide coupler for high index contrast systems

A coupler to efficiently transfer broadband light from a single-mode optical fiber to a single-mode high-index contrast waveguide has been fabricated on a silicon substrate. We utilized a novel coupling scheme, with a vertically asymmetric design consisting of a stepwise parabolic graded index profi...

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Bibliographic Details
Published in:Applied physics letters 2006-02, Vol.88 (8), p.081112-081112-3
Main Authors: Nguyen, Victor, Montalbo, Trisha, Manolatou, Christina, Agarwal, Anu, Hong, Ching-yin, Yasaitis, John, Kimerling, L. C., Michel, Jurgen
Format: Article
Language:English
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Summary:A coupler to efficiently transfer broadband light from a single-mode optical fiber to a single-mode high-index contrast waveguide has been fabricated on a silicon substrate. We utilized a novel coupling scheme, with a vertically asymmetric design consisting of a stepwise parabolic graded index profile combined with a horizontal taper, to simultaneously confine light in both directions. Coupling efficiency has been measured as a function of the device dimensions. The optimal coupling efficiency is achieved for structures whose length equals the focal distance of the graded index and whose input width is close to the mode field diameter of the fiber. The fabricated structure is compact, robust and highly efficient, with an insertion loss of 2.2 dB at 1550 nm . The coupler exhibits less than 1 dB variation in coupling efficiency in the measured spectral range from 1520 nm to 1620 nm . The lowest insertion loss of 1.9 dB is measured at 1540 nm . The coupler design offers highly efficient coupling for single mode waveguides of core indices up to 2.2.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.2179129