中文摘要：

基于耦合模理论和阶跃折射率单模光纤三层模型包层模理论，可在长周期光纤光栅（LPG）光纤包层外涂制特定的抗体作为生物活性膜层，并通过生物活性膜层折射率的变化来检验血液中是否存在对应的抗原。研究结果表明，当在LPG内部引入啁啾后。可提高LPG传感器的谐振波长偏移的灵敏度。但透射光强峰值会有相应的下降；随着啁啾参数的增加，透射光强峰值变化不大，谐振波长偏移随折射率的变化更为敏感。但当啁啾参数达到一定的量值时。这种偏移量相对较小。实验选用折射率同抗原、抗体接近的硅化膜作为成膜基底材料，基底膜层厚度可选择在约120nm，此时的波长位移线性度好。有利于实验中的测定。

英文摘要：

According to the Coupling Mode Theory （CMT） and the simplified three-layered model of the step-index single mode optical fiber, the variation of the bioactive layer refractive index may be used to detect whether the corresponding antigen is in blood by coating an idiosyncratic bioactive layer on the cladding of Long Period fiber Gratings （LPG）. The results show that, with the introduction of chirp in LPG, the sensitivity of the resonant wavelength shift is improved, but the peak of transmission intensity is lowered. With the further increase of chirp, the peak of transmission intensity varies little and the resonant wavelength shift becomes more sensitive. The variation of wavelength shift is decreased gradually when the chirp reaches a certain magnitude. Silicious layer is used as fundus layer since its refractive index is much the same as that of antigen and antibody. The thickness of fundus layer is about 120nm, which amounts to the ideal linear scale of wavelength shift for better measurements.