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Proceedings Paper

Polymer wedge for perfectly vertical light coupling to silicon
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Paper Abstract

We present the design and fabrication of a refractive polymer wedge that allows perfectly vertical coupling of light into a silicon waveguide, which is of interest for flip-chip bonding of vertical cavity emitting light sources on a silicon integrated circuit. The structure includes a conventional diffractive grating coupler that requires off-normal incidence to avoid second order Bragg reflections. The polymer wedge is thus used to refract vertically impinging light into an off-normal wave that couples into the underlying grating. The fabrication involves two steps: mold fabrication and imprint replication. Firstly negative wedge-shaped craters are etched into a quartz mold by Focused-ion-beam milling. Secondly the mold is used to imprint a UV-curable polymer onto a silicon chip containing waveguides and grating couplers, and so replicating the wedges. The characterization setup consisted of a fiber-to-fiber transmission measurement of a silicon waveguide equipped with a pair of grating couplers and polymer wedges. The obtained fiber coupling efficiency was equal to the efficiency of regular grating couplers and fiber positioned at an off-normal angle. The proposed fabrication method enables low cost integration of vertical cavity emitting light sources on silicon integrated photonic circuits.

Paper Details

Date Published: 10 February 2009
PDF: 8 pages
Proc. SPIE 7218, Integrated Optics: Devices, Materials, and Technologies XIII, 72180B (10 February 2009); doi: 10.1117/12.807558
Show Author Affiliations
J. Schrauwen, Ghent Univ. (Belgium)
S. Scheerlinck, Ghent Univ. (Belgium)
D. Van Thourhout, Ghent Univ. (Belgium)
R. Baets, Ghent Univ. (Belgium)


Published in SPIE Proceedings Vol. 7218:
Integrated Optics: Devices, Materials, and Technologies XIII
Jean-Emmanuel Broquin; Christoph M. Greiner, Editor(s)

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