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9 September 2008 Optofluidic evanescent sensing by polymer photonic crystal band edge lasers
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Organic dye doped polymer photonic crystal band-edge lasers, fabricated by combined nanoimprint and photolithography, are applied as evanescent-wave refractometry sensors. The emission characteristics of the lasers are altered in two ways, when the refractive index of the cladding is changed. Not only does the emission wavelength change, with a sensitivity of 1 nm per 10-2 refractive index units, but also the relative emission intensity along the two symmetry directions of the rectangular device. The latter phenomenon is caused by the interplay between the symmetry of the triangular photonic crystal lattice and the rectangular device shape. This causes two of the three emission axes expected from the photonic crystal geometry to collapse into one. The optical losses of these two modes are influenced in different ways when the refractive index of the cladding is altered, thus also causing the emitted intensities along the symmetry directions to change. This suggests an integrated sensing scheme, where intensity is measured rather than emission wavelength. Since intensity measurements are simpler to integrate than spectrometers, the concept can be implemented in compact lab-on-a-chip systems.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Mads Brøkner Christiansen, Felipe Bernal Arango, Morten Gersborg-Hansen, and Anders Kristensen "Optofluidic evanescent sensing by polymer photonic crystal band edge lasers", Proc. SPIE 7039, Nanoengineering: Fabrication, Properties, Optics, and Devices V, 70390F (9 September 2008);


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