导模共振生物传感器由于具有微型化、免标签、高通量和实时检测等优势被广泛研究.利用严格耦合波理论分析了该生物传感器对样品折射率和厚度的灵敏度随共振波长的变化规律.当样品厚度和共振波长一定时,其折射率灵敏度恒定；随着共振波长的增大,折射率灵敏度显著提高.当样品折射率和共振波长一定时,厚度灵敏度随着厚度的增加而降低,最后趋近于0；当共振波长增加时,厚度灵敏度明显提高,厚度测量范围增大.结果表明:选取较长的共振波长有利于样品的检测和分析.%Resonant grating waveguide (RGW) biosensor has been widely investigated in recent years. The system has several advantages such as minimizing, label-free, high throughput, real time monitoring and so on. The sensitivity of RGW biosensor was theoretically analyzed for different resonance wavelength. Sensitivity to the refractive index and thickness of the sample was analyzed using rigorous coupled wave analysis method. Results indicate that the sensitivity to refractive index is constant for a certain resonance wavelength as the thickness of sample does not change. The sensitivity to refractive index is enhanced with the increase of resonance wavelength. RGW with 1 250 nm resonance wavelength is approximately 4 times as sensitive as RGW with 830 nm resonance wavelength. The sensitivity to thickness drastically decreased at first, and then achieved zero for a certain resonance wavelength as the refractive index of sample is invariable. It was showed that it is limited to test sample thickness for every RGW. RGW with 1 250 nm resonance wavelength is approximately 2 times the measure range as RGW with 830 nm resonance wavelength. The sensitivity to thickness is enhanced with the increase of resonance wavelength. RGW with 1 250 nm resonance wavelength is approximately 3 times as sensitive as RGW with 830 nm resonance wavelength. The above results reveal that the sensitivity to both sample refractive index and sample thickness is enhanced with the increase of resonance wavelength. And the capability of testing sample thickness improves with longer resonance wavelength. The results provided the theory basis for resonance wavelength choice of RGW biosensor.
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