一种基于光子晶体的糖溶液检测仪的设计

Design of Sugar Solution Detector Based on Photonic Crystals

为设计糖溶液浓度检测仪,由Li F和Si介质组成了一含缺陷层的光子晶体。在考虑两介质色散关系的基础上,利用传输矩阵法对其透射特性进行了研究,计算表明,此光子晶体在400-700 nm的范围内出现了一个透射率为1的缺陷模,此缺陷模有如下特征：缺陷层中糖溶液浓度变化,不影响缺陷模的透射率和半峰全宽度,只改变缺陷模的中心位置,且糖溶液浓度与缺陷模的中心波长呈线性关系。两介质几何厚度分别或同时增加,缺陷模的透射率和半峰全宽度均不变,但其中心位置红移,移动率分别保持不变;Li F单独变化时,中心位置的移动率最小,Li F和Si同时变化时,移动率最大。不同介质几何厚度变化时,糖溶液浓度与缺陷模的中心波长呈不同的线性关系,但可通过重新定标来确定。

In order to design a sugar solution concentration detector, a photonic crystals containing a defect layer was composed by LiF and Si . Taking consideration of the dispersion relation of the mediums , transmission characteristics was researched by the transfer matrix method. The results show that there exits a defect mode of 1 transmittance in the range of 400-700 nm. This defect mode has following characteristics： the change of the concentration of sugar solution in defect layer does not affect the transmittance and the full width at half maximum （FWHM）, but the central position of defect mode is effected, and relationship between the solution of the sugar concentration and the position of defect mode is linear. The central position of defect mode occurs red shift with increasing the thickness of the mediums layer respectively or simultaneously, while both the transmittance and FWHM remain constant, and the mobile rate are constants. When LiF change alone, the mobile rate of the central position is minimum; when LiF and Si change simultaneously, the mobile rate is maximum. When the geometrical thickness of different mediums change, the concentration of the sugar solution and the central wavelength of the defect mode have different linear relationship, but it can be determined by re-scaling.