Planar waveguide photonic crystals as an alternative for refractive index optical sensors design: theoretical evaluation

Abstract

In this paper, the possibilities of designing refraction index optical sensors in planar waveguide photonic crystals are demonstrated for the first time. Photonic crystals obtained by connecting in cascade planar optical waveguides with high index contrast are analyzed. Photonic band gaps (PBGs) and photonic windows (PWs) were obtained. If a local defect is introduced in the PBG structure, the optical path length is modified and on states can be created in the gap. Besides, the on states wavelengths can be tuned if the optical path of the defect is modified: changing the physical length and/or the refraction index of the defect. In this way, planar waveguide photonic crystals could be used for sensing applications when a specimen modifies the refraction index lattice site. Sensing properties of planar waveguide photonic crystals, with one, two and three sensing channels, are demonstrated.

Keywords:

• optical waveguides
• photonic crystals
• optical sensors

Acknowledgements

This work was supported by the Project from MEC: TEC2005-05541. Thanks to Arcelor and Saint Gobaint Companies for technical assistance.