We demonstrate a novel hybrid system, the two-dimensionally periodic photonic-crystal slab[1], that is much more amenable to fabrication at optical lengthscales than three-dimensionally periodic systems with full band gaps, but retains or approximates the desirable properties of the latter. Such hybrid structures promise easier realization of PBGs for applications such as integrated optical circuits. Photonic-crystal slabs are three-dimensional structures that use conventional index-guiding to confine light vertically and a two-dimensional photonic-crystal structure to confine light horizontally. We describe a theoretical band-structure framework for understanding slab crystals, and show how they fundamentally differ from two- and three-dimensional photonic crystals. The effects of the light cone and the introduction of the slab thickness as a new critical parameter are analyzed, and unique considerations are described for achieving resonant cavities[2] and linear waveguides[3] in slab structures. We also present the results of experimental work[4] that confirms the theoretical results, and which realizes photonic band-gap effects and three-dimensional control of light at optical wavelengths. We describe integrated-optical components that could be achieved with photonic band-gap effects, including novel designs for low-loss waveguide crossings[5] and branchings[6].

References:

[1] S. G. Johnson, S. Fan, P. R. Villeneuve, J. D. Joannopoulos, L. A. Kolodziejski, "Guided modes in photonic crystal slabs," Phys. Rev. B 60, 5751-5758 (1999).

[2] P. R. Villeneuve, S. Fan, S. G. Johnson, and J. D. Joannopoulos, "Three-dimensional photon confinement in photonic crystals of low-dimensional periodicity" IEE Proc. Optoelec. 145, 384 (1998).

[3] S. G. Johnson, Pierre R. Villeneuve, S. Fan, J. D. Joannopoulos, "Linear waveguides in photonic-crystal slabs," submitted for publication in Phys. Rev. B.

[4] Edmond Chow, S. Y. Lin, S.G. Johnson, P. R. Villeneuve, J. D. Joannopoulos, J. R. Wendt, G. A. Vawter, W. Zurzycki, H. Hou, and A. Alleman, "Three-dimensional Control of Light in a Two-dimensionally Periodic Photonic-Crystal Slab," to be submitted for publication in Nature.

[5] S. G. Johnson, C. Manolatou, S. Fan, P. R. Villeneuve, J. D. Joannopoulos, and H. A. Haus, "Elimination of cross talk in waveguide intersections," Optics Letters 23, 1855-1857 (1998).

[6] S. Fan, S. G. Johnson, J. D. Joannopoulos, C. Manolatau, H. A. Haus, "Waveguide branches in photonic crystals," to be submitted for publication.