The Two-Dimension Photonic Crystal Biosensing Technology Based On Spectral Imaging

At present, the study about the dynamics combined with tiny molecules, analysis onlow concentration biological molecules and interaction between low affinity biologicalmolecules is still difficulty. But the biosensor based on photonic crystal optical imagingtechniques provides the ideal conditions and pattern to solve this problem, for its highsensitivity when used to analyze the spectrum band. The photonic crystal biosensorsplayed a unique advantage especially in the‘naked eye detection technology’.Rigorous coupled wave analysis (RCWA) is a kind of vector analysis method, canaccurately describe the diffraction from grating and effectively analyze surface anaglyphgrating. The two-dimension photonic crystal can be regard as a special subwavelengthgrating. So in this paper the diffraction efficiency of white light narrowband spectrumwhich reflected from the substrate of two-dimension photonic crystal is caculated byrigorous coupled wave analysis.The sensitivity of biosensor must be high, for it often need to work under highsignal-to-noise to detect low concentration analyte and interaction between smallmolecular. There are three factors influence the sensitivity of photonic crystal biosensor——grating period , effective refractive index and testing area . According to thesefactors we compared how different grating period and effective reflective index influencethe white light narrowband peak value of reflection spectrum and full width at halfmaximum. As a result, we got a structure of two-dimension photonic crystal that iscomparatively suitable for biosensor.In this paper a kind of two-dimension photonic crystal biosensor system is designed.A similar Michelson interferometer structure is used to control optical path. The opticalpath difference of Michelson interferometer is modulated by PZT piezoelectric sensor,which is controlled by computer program. Then spectrum imaging at the CCD surface,that means the completion of spectrum signal acquisition. At last make spectrum imagereconstruction and color marked by software, to conveniently observe the solutioninformation which fill at the photonic crystal surface. Using the DiffracMOD module in optical passive software——RSoft to simulate thewhite light narrowband reflection spectrum from two-dimention photonic crystal. In thispaper we give different concentration sucrose solution, ethanol solution and seawater,simulate the reflection when these solution filled in the surface of photonic crystalbisensor, then we can get the peak drift. And according to the ralationship betweenconcentration and reflective index, we can determine the ralationship between solutionconcentration and peak value of reflction spectrum. That provide basis for using photoniccrystal biosensor detect solution concentration. And in order to observe the peak driftmore conveniently and visually, we show the results through color code.