改变光栅及其衬底厚度对导模共振传感的影响

Study on Sensor of the Guided-mode Resonance Influenced by the Thicknesses of the Subwavelength Grating and Its Base

采用严格耦合波法与时域有限差分法数值模拟仿真相结合的办法,对由亚波长光栅及其衬底厚度变化影响的导模共振传感进行了研究。其结果表明:1、在优化光栅膜厚的基础上,通过改变光栅衬底厚度来调节导模共振的产生位置处于由于该膜厚变化产生的背景反射极小位置处时,可使导模共振峰的旁带抑制比提高,从而提高该光栅传感器的分辨率;2、在对高折射率样品进行检测时,该光栅传感器的分辨率、灵敏度均较折射率低样品好,但由于高折射率样品导致导模共振场的局域性增强,从而导致获得的反射率降低。

A combination of the rigorous coupled-wave analysis method(RCWA)and finite time-domain method(FDTD)is used for calculation.The results indicate that the sensor resolution can be improved by adjusting the grating thickness and can be further improved by adjusting its base thickness.With change of the base thickness,as the position of guided mode resonance(GMR)is where the destructive inferference of background produces,the sideband rejection ratio of the resonant peak is enhanced,then the resolution is improved.Secondly,when detecting the sample with higher RI,its sensitivity and resolution are better than that with lower RI.However,the sample with higher RI brings about the local enhancement of guided mode resonance field,thus resulting in the decease of reflection ratio.