Graded-lattice AAO photonic crystal heterostructure for high Q refractive index sensing

We present a low-cost and versatile optical sensor based on anodic aluminum oxide (AAO) graded-lattice photonic crystal heterostructure (PCH) template controlled by voltage pulse and electrolyte temperature. Designed PCH shows high Q factor up to similar to 55 from the first order side band peak in the reflectance spectra and vivid color change due to infiltrated analytes. Highly linear refractive index sensitivity d lambda/dn up to 441 nm RIU-1 could be obtained independent of analytes' polarities. Superb perceptual colorimetric sensing performance was attained up to 0.01 according to CIELab tristimulus mapping analysis.