Abstract

Compact metal grating couplers for efficient and broadband coupling between optical fibers and silicon-on-insulator waveguides are proposed and demonstrated. Simulation results for silver, gold, aluminum and copper grating couplers are presented. Using a uniform silver grating, coupling efficiencies are calculated as high as 60 % at a wavelength of 1.55 µm. Metal grating couplers require only one single etching or lift-off step and are therefore very easy to fabricate. As a proof of principle, a gold grating coupler for near-vertical fiber-to-waveguide coupling was fabricated using e-beam writing and lift-off, demonstrating 34 % coupling efficiency and a 1 dB-bandwidth of 40 nm. Measurement data and simulation results are in good agreement.

© 2007 Optical Society of America

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References

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  1. W. Bogaerts, R. Baets, P. Dumon, V. Wiaux, S. Beckx, D. Taillaert, B. Luyssaert, J. Van Campenhout, P. Bienstman, and D. Van Thourhout, "Nanophotonic waveguides in silicon-on-insulator fabricated with CMOS technology," J. Lightwave Technol. 23, 401-412 (2005).
    [CrossRef]
  2. D. Taillaert, P. Bienstman, and R. Baets, "Compact efficient broadband grating coupler for silicon-on-insulator waveguides," Opt. Lett. 29, 2749--2751 (2004).
    [CrossRef] [PubMed]
  3. D. Taillaert, R. Baets, P. Dumon, W. Bogaerts, D. Van Thourhout, B. Luyssaert, V. Wiaux, S. Beckx, J. Wouters, "Silicon-on-Insulator platform for integrated wavelength-selective Components," Proc. of IEEE/LEOS Workshop on Fibers and Optical Passive Components, 115--120 (2005).
    [CrossRef]
  4. F. Van Laere, G. Roelkens, M. Ayre, J. Schrauwen, D. Taillaert, D. Van Thourhout, T. F. Krauss, and R. Baets, "Compact and highly efficient grating couplers between optical fiber and nanophotonic waveguides," J. Lightwave Technol. 25, 151--156 (2007).
    [CrossRef]
  5. G. Roelkens, D. Van Thourhout, and R. Baets, "High efficiency Silicon-on-Insulator grating coupler based on a poly-Silicon overlay," Opt. Express,  14, 11622--11630 (2006).
    [CrossRef] [PubMed]
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    [CrossRef]
  7. P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B 6,4370-4379 (1972).
    [CrossRef]
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    [CrossRef]
  10. T. Suhara and H. Nishihara, "Integrated optics components and devices using periodic structures," IEEE J. Quantum Electron. 22, 845-867 (2002).
    [CrossRef]
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  12. R. Waldhausl, B. Schnabel, P. Dannberg, E. Kley, A. Brauer, W. Karthe, "Efficient coupling into polymer waveguides by gratings," Appl. Opt. 36, 9383-9390 (1997).
    [CrossRef]

2007 (1)

2006 (1)

2005 (1)

2004 (1)

2002 (1)

T. Suhara and H. Nishihara, "Integrated optics components and devices using periodic structures," IEEE J. Quantum Electron. 22, 845-867 (2002).
[CrossRef]

2001 (1)

P. Bienstman and R. Baets, "Optical modeling of photonic crystals and VCSEL's using eigenmode expansion and perfectly matched layers," Opt. Quantum Electron. 33, 349-354 (2001).
[CrossRef]

1997 (1)

1993 (1)

1992 (1)

R. Emmons and D. Hall, "Buried-oxide silicon-on-insulator structures II: Waveguide grating couplers," IEEE J. Quantum Electron. 28, 164-175 (1992).
[CrossRef]

1972 (1)

P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B 6,4370-4379 (1972).
[CrossRef]

Ayre, M.

Baets, R.

Bates, K. A.

Beckx, S.

Bienstman, P.

Bogaerts, W.

Brauer, A.

Burke, J.

Christy, R. W.

P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B 6,4370-4379 (1972).
[CrossRef]

Dannberg, P.

Dumon, P.

Emmons, R.

R. Emmons and D. Hall, "Buried-oxide silicon-on-insulator structures II: Waveguide grating couplers," IEEE J. Quantum Electron. 28, 164-175 (1992).
[CrossRef]

Hall, D.

R. Emmons and D. Hall, "Buried-oxide silicon-on-insulator structures II: Waveguide grating couplers," IEEE J. Quantum Electron. 28, 164-175 (1992).
[CrossRef]

Johnson, P. B.

P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B 6,4370-4379 (1972).
[CrossRef]

Karthe, W.

Kley, E.

Krauss, T. F.

Li, L.

Luyssaert, B.

Nishihara, H.

T. Suhara and H. Nishihara, "Integrated optics components and devices using periodic structures," IEEE J. Quantum Electron. 22, 845-867 (2002).
[CrossRef]

Roelkens, G.

Roncone, R.

Schnabel, B.

Schrauwen, J.

Suhara, T.

T. Suhara and H. Nishihara, "Integrated optics components and devices using periodic structures," IEEE J. Quantum Electron. 22, 845-867 (2002).
[CrossRef]

Taillaert, D.

Van Campenhout, J.

Van Laere, F.

Van Thourhout, D.

Waldhausl, R.

Wiaux, V.

Appl. Opt. (2)

J. Lightwave Technol. (2)

J. Quantum Electron. (2)

R. Emmons and D. Hall, "Buried-oxide silicon-on-insulator structures II: Waveguide grating couplers," IEEE J. Quantum Electron. 28, 164-175 (1992).
[CrossRef]

T. Suhara and H. Nishihara, "Integrated optics components and devices using periodic structures," IEEE J. Quantum Electron. 22, 845-867 (2002).
[CrossRef]

Opt. Express (1)

Opt. Lett. (1)

Opt. Quantum Electron. (1)

P. Bienstman and R. Baets, "Optical modeling of photonic crystals and VCSEL's using eigenmode expansion and perfectly matched layers," Opt. Quantum Electron. 33, 349-354 (2001).
[CrossRef]

Phys. Rev. B (1)

P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B 6,4370-4379 (1972).
[CrossRef]

Other (2)

E. D. Palik, "Handbook of Optical Constants of Solids," Academic Press Inc. (1985), ISBN 0-12-544420-6.

D. Taillaert, R. Baets, P. Dumon, W. Bogaerts, D. Van Thourhout, B. Luyssaert, V. Wiaux, S. Beckx, J. Wouters, "Silicon-on-Insulator platform for integrated wavelength-selective Components," Proc. of IEEE/LEOS Workshop on Fibers and Optical Passive Components, 115--120 (2005).
[CrossRef]

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Figures (6)

Fig. 1.
Fig. 1.

Metal grating on top of an SOI-waveguide for coupling to a single mode optical fiber. (a) Device layout (side view), (b) SEM-image of a fabricated device (top view, bar length=5 µm).

Fig. 2.
Fig. 2.

Simulation of metal grating directionality as a function of grating height. The metal is silver. Buried oxide layer thickness is 1.35 µ m. Period of the grating is 610 nm.

Fig. 3.
Fig. 3.

Field plot for an optimized uniform silver grating. Grating period=610 nm, filling factor=30 %, thickness of the silver layer=20 nm, buried oxide layer thickness=1.35 µm.

Fig. 4.
Fig. 4.

Simulation of the coupling efficiency for silver, gold, aluminum and copper grating couplers for SOI waveguides. Grating period=610 nm, filling factor=30 %, grating height=20 nm, buried oxide layer thickness=1.35 µm, fiber tilt=9 degrees.

Fig. 5.
Fig. 5.

Simulation of the coupling efficiency of a silver grating coupler as a function of buried oxide layer thickness.

Fig. 6.
Fig. 6.

Experimentally determined fiber-to-waveguide coupling efficiency of a gold grating coupler with parameters: period=630 nm, filling factor=30 %, grating height=20 nm with a 3 nm Ti adhesion on top of an SOI waveguide using a single-mode fiber tilted 10 degrees with respect to the vertical. CAMFR-simulation results are added for comparison.

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