Abstract

We present the design, fabrication and measurement of photonic crystal directional couplers in the InP/InGaAsP/InP material system. A comprehensive analysis of the dependence of the coupling length and usable wave-length range on the diameter of the holes next to the waveguides is given. The possibility to trade-off coupling length against usable wavelength range is shown. Designs with coupling lengths as low as 52 lattice constants and with an operation range covering 16% of the bandgap width are fabricated and measured. Good agreement between optimized and measured devices is achieved.

© 2007 Optical Society of America

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References

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  1. J. D. Joannopoulos, R. D. Meade, and J. N. Winn, Photonic Crystals - Molding the flow of light (1995).
  2. A. Xing, M. Davanço, D. J. Blumenthal, and E. L. Hu, "Transmission measurement of tapered single-line defect photonic crystal waveguides," IEEE Photon. Technol. Lett. 17, 2092-2094 (2005).
    [CrossRef]
  3. M. Loncar, D. Nedeljkovic, T. Doll, J. Vuckovic, A. l. Scherer, and T. P. Pearsall, "Waveguiding in planar photonic crystals," Appl. Phys. Lett. 77, 1937-1939 (2000).
    [CrossRef]
  4. K. Rauscher, Simulation, design and characterisation of photonic crystal devices in a low vertical index contrast regime, Diss. ETH Nr. 16516, Electr. Eng. ETH Zürich, 2006.
  5. Y. Tanaka, H. Nakamura, Y. Sugimoto, N. Ikeda, K. Asakawa, and K. Inoue, "Coupling properties in a 2-D photonic crystal slab directional coupler with a triangular lattice of air holes," IEEE J. Quantum Electron. 41, 76-84 (2005).
    [CrossRef]
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    [CrossRef]
  7. A. Sharkawy, S. Shi, and D. W. Prather, "Electro-optical switching using coupled photonic crystal waveguides," Opt. Express 10, 1048-1059 (2002).
    [PubMed]
  8. S. Boscolo, M. Midrio, and C. G. Someda, "Coupling and decoupling of electromagnetic waves in parallel 2D photonic crystal waveguides," IEEE J. Quantum Electron. 38, 47 - 53 (2002).
    [CrossRef]
  9. A. Martinez, F. Cuesta, and J. Marti, "Ultrashort 2-D photonic crystal directional couplers," IEEE Photon. Technol. Lett. 15, 694-696 (2003).
    [CrossRef]
  10. M. Tokushima and H. Yamada, "Photonic crystal line defect waveguide directional coupler," Electron. Lett. 37, 1454 - 1455 (2001).
    [CrossRef]
  11. D. Leuenberger, R. Ferrini, L. A. Dunbar, R. Houdré, M. Kamp, and A. Forchel, "Codirectional couplers in GaAs-based planar photonic crystals," Appl. Phys. Lett. 86, 081108 (2005).
    [CrossRef]
  12. M. Qiu, M. Mulot, M. Swillo, S. Anand, B. Jaskorzynska, A. Karlsson, M. Kamp, and A. Forchel, "Photonic crystal optical filter based on contra-directional waveguide coupling," Appl. Phys. Lett. 83, 5121-5123 (2003).
    [CrossRef]
  13. M. Thorhauge, L. H. Frandsen, and P. I. Borel, "Efficient photonic crystal directional couplers," Opt. Lett. 28, 1525-1527 (2003).
    [CrossRef] [PubMed]
  14. M. Qiu, "Effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals," Appl. Phys. Lett. 81, 1163-1165 (2002).
    [CrossRef]
  15. S. G. Johnson, and J. D. Joannopoulos, "Block-iterative frequency-domain methods for Maxwell's equations in a planewave basis," Opt. Express 8, 173-190 (2001).
    [CrossRef] [PubMed]
  16. R. Wüest, F. Robin, C. Hunziker, P. Strasser, D. Erni, and H. Jäckel, "Limitations of proximity-effect corrections for electron-beam patterning of planar photonic crystals," Opt. Eng. 44, 043401 (2005).
    [CrossRef]
  17. R. Wüest, P. Strasser, F. Robin, D. Erni, and H. Jäckel, "Fabrication of a hard mask for InP based photonic crystals: Increasing the plasma-etch selectivity of poly(methyl methacrylate) versus SiO2 and SiNx," J. Vac. Sci. Technol. B 23, 3197-3201 (2005).
    [CrossRef]
  18. P. Strasser, R. Wüest, F. Robin, D. Erni, and H. Jäckel, "A detailed analysis of the influence of an ICP-RIE process on the hole depth and shape of photonic crystals in InP/InGaAsP " J. Vac. Sci. Technol. B 25, 387-393 (2007)
    [CrossRef]

2007 (1)

P. Strasser, R. Wüest, F. Robin, D. Erni, and H. Jäckel, "A detailed analysis of the influence of an ICP-RIE process on the hole depth and shape of photonic crystals in InP/InGaAsP " J. Vac. Sci. Technol. B 25, 387-393 (2007)
[CrossRef]

2005 (5)

R. Wüest, F. Robin, C. Hunziker, P. Strasser, D. Erni, and H. Jäckel, "Limitations of proximity-effect corrections for electron-beam patterning of planar photonic crystals," Opt. Eng. 44, 043401 (2005).
[CrossRef]

R. Wüest, P. Strasser, F. Robin, D. Erni, and H. Jäckel, "Fabrication of a hard mask for InP based photonic crystals: Increasing the plasma-etch selectivity of poly(methyl methacrylate) versus SiO2 and SiNx," J. Vac. Sci. Technol. B 23, 3197-3201 (2005).
[CrossRef]

A. Xing, M. Davanço, D. J. Blumenthal, and E. L. Hu, "Transmission measurement of tapered single-line defect photonic crystal waveguides," IEEE Photon. Technol. Lett. 17, 2092-2094 (2005).
[CrossRef]

Y. Tanaka, H. Nakamura, Y. Sugimoto, N. Ikeda, K. Asakawa, and K. Inoue, "Coupling properties in a 2-D photonic crystal slab directional coupler with a triangular lattice of air holes," IEEE J. Quantum Electron. 41, 76-84 (2005).
[CrossRef]

D. Leuenberger, R. Ferrini, L. A. Dunbar, R. Houdré, M. Kamp, and A. Forchel, "Codirectional couplers in GaAs-based planar photonic crystals," Appl. Phys. Lett. 86, 081108 (2005).
[CrossRef]

2003 (3)

M. Qiu, M. Mulot, M. Swillo, S. Anand, B. Jaskorzynska, A. Karlsson, M. Kamp, and A. Forchel, "Photonic crystal optical filter based on contra-directional waveguide coupling," Appl. Phys. Lett. 83, 5121-5123 (2003).
[CrossRef]

A. Martinez, F. Cuesta, and J. Marti, "Ultrashort 2-D photonic crystal directional couplers," IEEE Photon. Technol. Lett. 15, 694-696 (2003).
[CrossRef]

M. Thorhauge, L. H. Frandsen, and P. I. Borel, "Efficient photonic crystal directional couplers," Opt. Lett. 28, 1525-1527 (2003).
[CrossRef] [PubMed]

2002 (3)

A. Sharkawy, S. Shi, and D. W. Prather, "Electro-optical switching using coupled photonic crystal waveguides," Opt. Express 10, 1048-1059 (2002).
[PubMed]

M. Qiu, "Effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals," Appl. Phys. Lett. 81, 1163-1165 (2002).
[CrossRef]

S. Boscolo, M. Midrio, and C. G. Someda, "Coupling and decoupling of electromagnetic waves in parallel 2D photonic crystal waveguides," IEEE J. Quantum Electron. 38, 47 - 53 (2002).
[CrossRef]

2001 (3)

2000 (1)

M. Loncar, D. Nedeljkovic, T. Doll, J. Vuckovic, A. l. Scherer, and T. P. Pearsall, "Waveguiding in planar photonic crystals," Appl. Phys. Lett. 77, 1937-1939 (2000).
[CrossRef]

Appl. Phys. Lett. (4)

M. Loncar, D. Nedeljkovic, T. Doll, J. Vuckovic, A. l. Scherer, and T. P. Pearsall, "Waveguiding in planar photonic crystals," Appl. Phys. Lett. 77, 1937-1939 (2000).
[CrossRef]

D. Leuenberger, R. Ferrini, L. A. Dunbar, R. Houdré, M. Kamp, and A. Forchel, "Codirectional couplers in GaAs-based planar photonic crystals," Appl. Phys. Lett. 86, 081108 (2005).
[CrossRef]

M. Qiu, M. Mulot, M. Swillo, S. Anand, B. Jaskorzynska, A. Karlsson, M. Kamp, and A. Forchel, "Photonic crystal optical filter based on contra-directional waveguide coupling," Appl. Phys. Lett. 83, 5121-5123 (2003).
[CrossRef]

M. Qiu, "Effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals," Appl. Phys. Lett. 81, 1163-1165 (2002).
[CrossRef]

Electron. Lett. (1)

M. Tokushima and H. Yamada, "Photonic crystal line defect waveguide directional coupler," Electron. Lett. 37, 1454 - 1455 (2001).
[CrossRef]

IEEE J. Quantum Electron. (2)

Y. Tanaka, H. Nakamura, Y. Sugimoto, N. Ikeda, K. Asakawa, and K. Inoue, "Coupling properties in a 2-D photonic crystal slab directional coupler with a triangular lattice of air holes," IEEE J. Quantum Electron. 41, 76-84 (2005).
[CrossRef]

S. Boscolo, M. Midrio, and C. G. Someda, "Coupling and decoupling of electromagnetic waves in parallel 2D photonic crystal waveguides," IEEE J. Quantum Electron. 38, 47 - 53 (2002).
[CrossRef]

IEEE Photon. Technol. Lett. (2)

A. Martinez, F. Cuesta, and J. Marti, "Ultrashort 2-D photonic crystal directional couplers," IEEE Photon. Technol. Lett. 15, 694-696 (2003).
[CrossRef]

A. Xing, M. Davanço, D. J. Blumenthal, and E. L. Hu, "Transmission measurement of tapered single-line defect photonic crystal waveguides," IEEE Photon. Technol. Lett. 17, 2092-2094 (2005).
[CrossRef]

J. Lightwave Technol. (1)

J. Vac. Sci. Technol. B (2)

R. Wüest, P. Strasser, F. Robin, D. Erni, and H. Jäckel, "Fabrication of a hard mask for InP based photonic crystals: Increasing the plasma-etch selectivity of poly(methyl methacrylate) versus SiO2 and SiNx," J. Vac. Sci. Technol. B 23, 3197-3201 (2005).
[CrossRef]

P. Strasser, R. Wüest, F. Robin, D. Erni, and H. Jäckel, "A detailed analysis of the influence of an ICP-RIE process on the hole depth and shape of photonic crystals in InP/InGaAsP " J. Vac. Sci. Technol. B 25, 387-393 (2007)
[CrossRef]

Opt. Eng. (1)

R. Wüest, F. Robin, C. Hunziker, P. Strasser, D. Erni, and H. Jäckel, "Limitations of proximity-effect corrections for electron-beam patterning of planar photonic crystals," Opt. Eng. 44, 043401 (2005).
[CrossRef]

Opt. Express (2)

Opt. Lett. (1)

Other (2)

J. D. Joannopoulos, R. D. Meade, and J. N. Winn, Photonic Crystals - Molding the flow of light (1995).

K. Rauscher, Simulation, design and characterisation of photonic crystal devices in a low vertical index contrast regime, Diss. ETH Nr. 16516, Electr. Eng. ETH Zürich, 2006.

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Figures (6)

Fig. 1.
Fig. 1.

Dispersion diagram of a W1 waveguide (blue dashed lines) and a DC (red lines) with reduced central hole radius (Fig. 2, design B, rc =0.25a), restricted to the upper half of the photonic bandgap. The shaded area represents the area of bulk photonic bands. The quasisingle- mode region is limited by airband modes lowered in frequency and the odd mode.

Fig. 2.
Fig. 2.

(a). Schematics of the three investigated coupler designs. (b). PWE simulations of OR and minimal CL. The red segments represent the DCs with edge hole radius re =0.31a for different central hole radii. The blue segments correspond to designs with edge hole radius to re =0.33a, re =0.35a and re =0.37a for the upper, middle and lower segment of each group, respectively.

Fig. 3.
Fig. 3.

FE simulations of the Hz field for coupler designs A and B (Fig. 2).

Fig. 4.
Fig. 4.

CL vs. reduced frequency simulated with the FE (empty blue diamonds) and PWE (filled red squares) techniques for the couplers with a central hole size rc =0.19a and different edge hole sizes. The change of the CL within the OR is below 10%.

Fig. 5.
Fig. 5.

SEM micrograph of a typical fabricated coupler. A W1 waveguide is preceding the DC and a short taper in the cross waveguide suppresses reflections between the W1 and the DC.

Fig. 6.
Fig. 6.

(a). Fitting of the measured normalized transmitted power for the bar (red filled squares) and cross (empty blue diamonds) states vs. device length. rc =0.19a, re =0.31a and u=0.271. (b). Comparison of the PWE simulation (dashed blue line) and measurements (red line) of the CL for the DCs with rc =0.19a.

Tables (1)

Tables Icon

Table 1. Comparison between target and fabricated hole sizes and impact on the CL by means of PWE simulations.

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