Abstract

In this paper, we demonstrate a 2-bit optical analog-to-digital (A/D) converter. This converter consists of three cascaded splitters constructed in a self-guiding photonic crystal through the perturbation of the uniform lattice. The A/D conversion is achieved by adjusting splitting ratios of the splitters through changing the degree of perturbation. In this way, output ports reach a state of ‘1’ at different input power levels to generate unique states desired for an A/D converter. To validate this design concept, we first experimentally characterize the relation between the splitting ratio and the degree of lattice perturbation. Based on this understanding, we then fabricate the 2-bit A/D converter and successfully observe four unique states corresponding to different power levels of input analog signal.

© 2006 Optical Society of America

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References

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  1. H. F Taylor, "Optical analog-to-digital converter - design and analysis," IEEE J. Sel. Top. Quantum Electron. 15, 210-216 (1979).
    [CrossRef]
  2. B. Jalali, and Y. M. Xie, "Optical folding-flash analog-to-digital converter with analog encoding," Opt. Lett. 20, 1901-1903 (1995).
    [CrossRef] [PubMed]
  3. M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
    [CrossRef]
  4. J. Cai, and G. W. Taylor, "Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator," Opt. Commun. 184, 79-88 (2000).
    [CrossRef]
  5. L. Brzozowski, and E. H. Sargent, "All-optical analog-to-digital converters, hardlimiters, and logic gates," J. Lightwave Technol. 19,114-119 (2001).
    [CrossRef]
  6. J. D. Joannopoulos, R. D. Meade, and J. N. Winn, Photonic Crystals: Molding the Flow of Light, (Princeton, N.J., Princeton University Press, 1995).
  7. S. G. Johnson, and J. D. Joannopoulos, "Block-Iterative Frequency-Domain Methods for Maxwell's Equations in a Plane Wave Basis," Opt. Express 8, 173-180 (2001).
    [CrossRef] [PubMed]
  8. C. Chen,  et al. "Engineering Dispersion Properties of Photonic Crystals for Spatial Beam Routing and Non-Channel Waveguiding," in Integrated Photonics Research, 2003 OSA Technical Digest (Optical Society of America, 2003).
  9. S. G. Johnson,  et al., "Guided modes in photonic crystal slabs," Phys. Rev. B. 60, 5751-5758 (1999).
    [CrossRef]
  10. J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
    [CrossRef]
  11. A. Taflove, and S. C. Hagness, Computational Electromagnetics: The Finite-Difference Time-Domain Method, (Boston, Artech House, 2000) 852.
  12. D. W. Prather,  et al., "High Efficiency Coupling Structure for a single Line-Defect Photonic Crystal Waveguide," Opt. Lett. 27,1601-1603 (2002).
    [CrossRef]

2002 (2)

J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
[CrossRef]

D. W. Prather,  et al., "High Efficiency Coupling Structure for a single Line-Defect Photonic Crystal Waveguide," Opt. Lett. 27,1601-1603 (2002).
[CrossRef]

2001 (2)

2000 (1)

J. Cai, and G. W. Taylor, "Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator," Opt. Commun. 184, 79-88 (2000).
[CrossRef]

1999 (1)

S. G. Johnson,  et al., "Guided modes in photonic crystal slabs," Phys. Rev. B. 60, 5751-5758 (1999).
[CrossRef]

1997 (1)

M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
[CrossRef]

1995 (1)

1979 (1)

H. F Taylor, "Optical analog-to-digital converter - design and analysis," IEEE J. Sel. Top. Quantum Electron. 15, 210-216 (1979).
[CrossRef]

Brzozowski, L.

Cai, J.

J. Cai, and G. W. Taylor, "Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator," Opt. Commun. 184, 79-88 (2000).
[CrossRef]

Esman, R. D.

M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
[CrossRef]

Frankel, M. Y.

M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
[CrossRef]

Jalali, B.

Joannopoulos, J. D.

Johnson, S. G.

Kang, J.

M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
[CrossRef]

Loncar, M.

J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
[CrossRef]

Prather, D. W.

Sargent, E. H.

Scherer, A.

J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
[CrossRef]

Taylor, G. W.

J. Cai, and G. W. Taylor, "Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator," Opt. Commun. 184, 79-88 (2000).
[CrossRef]

Taylor, H. F

H. F Taylor, "Optical analog-to-digital converter - design and analysis," IEEE J. Sel. Top. Quantum Electron. 15, 210-216 (1979).
[CrossRef]

Witzens, J.

J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
[CrossRef]

Xie, Y. M.

Electron. Lett. (1)

M. Y. Frankel, J. Kang, and R. D. Esman," High-performance photonic analogue-digital converter," Electron. Lett. 33, 2096-2097 (1997).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (2)

H. F Taylor, "Optical analog-to-digital converter - design and analysis," IEEE J. Sel. Top. Quantum Electron. 15, 210-216 (1979).
[CrossRef]

J. Witzens, M. Loncar, and A. Scherer, "Self-collimation in planar photonic crystals," IEEE J. Sel. Top. Quantum Electron. 8,1246-1257 (2002).
[CrossRef]

J. Lightwave Technol. (1)

Opt. Commun. (1)

J. Cai, and G. W. Taylor, "Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator," Opt. Commun. 184, 79-88 (2000).
[CrossRef]

Opt. Express (1)

Opt. Lett. (2)

Phys. Rev. B. (1)

S. G. Johnson,  et al., "Guided modes in photonic crystal slabs," Phys. Rev. B. 60, 5751-5758 (1999).
[CrossRef]

Other (3)

C. Chen,  et al. "Engineering Dispersion Properties of Photonic Crystals for Spatial Beam Routing and Non-Channel Waveguiding," in Integrated Photonics Research, 2003 OSA Technical Digest (Optical Society of America, 2003).

A. Taflove, and S. C. Hagness, Computational Electromagnetics: The Finite-Difference Time-Domain Method, (Boston, Artech House, 2000) 852.

J. D. Joannopoulos, R. D. Meade, and J. N. Winn, Photonic Crystals: Molding the Flow of Light, (Princeton, N.J., Princeton University Press, 1995).

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Figures (9)

Fig. 1.
Fig. 1.

Two-bit A/D converter consisting of three beam splitting structures in a self-guiding photonic crystal.

Fig. 2.
Fig. 2.

Concept of two-bit optical A/D converter.

Fig. 3.
Fig. 3.

Dispersion properties of the square lattice patterned in a silicon slab with the radii of air holes of 0.25a and the slab thickness of 0.5333a: (a) dispersion diagram, (b) equi-frequency contours of the second band.

Fig. 4.
Fig. 4.

(a) Beam propagation in a self-guiding lattice, (b) splitting self-guiding beam when the radius of the perturbed air holes is 0.4a, (c) reflecting self-guiding beam when the radius of the perturbed air holes is 0.45a.

Fig. 5.
Fig. 5.

Plot of output power verse radius of the perturbed air holes.

Fig. 6.
Fig. 6.

SEM pictures of three of the fabricated self-guiding splitters.

Fig. 7.
Fig. 7.

Characterization of self-guiding splitters: (a) the top-down images captured by an IR CCD camera for the case with the radius of the splitting structure of 368 nm at the wavelength of 1560 nm, (b) the measured relation between the output powers and the radius of splitting air holes.

Fig. 8.
Fig. 8.

Fabrication and characterization of a 2-bit A/D converter: (a) the SEM picture of the device, (b) the captured IR images of output ports at λ = 1560nm.

Fig. 9.
Fig. 9.

Plot of the measured output powers at output port I, II, III verse the incident power when it varies from 100μW to 1.5mW linearly.

Equations (1)

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V g = k ω ( K ) ,

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