Meanwhile, the position of the resonant wavelength can be obtaine

Meanwhile, the position of the resonant wavelength can be obtained.In our experiment, the structure parameters are as follows: the refraction index of the grating layer is nh = 1.98 (HfO2); nl = nc = 1.0 (air); the grating period �� is 500 nm; the substrate selleck products refraction index ns is 1.52 (quartz glass); the refraction index of the waveguide layer is nw = 1.98 (HfO2). According to these parameters, the range of the resonant wavelength we got to be 760 < �� < 990. Here, we choose �� = 800 nm. The anti-reflective conditions require the thicknesses of the waveguide layer and the grating layer to be one quarter-wavelength to optimize the structure. The thickness of the waveguide layer dw is 101 nm and the grating layer dg is 120 nm. At this point, all the structure parameters of the GMRF biosensor have been determined and are summarized in Table 1.
Table 1.Parameters of the GMR biosensor.3.?Results and DiscussionBased on the GMR structure we designed in the previous section, the electric field distribution can be obtained using the RCWA method. Here, a comparison of biosensor sensitivity for the TE and TM modes based on the distribution of electric fields is presented. According to the RCWA method, the resonant wavelength of incident light in the TE mode is 798 nm without a biological sample attached on the surface, while the resonant wavelength of the TM mode is 766 nm. Because the sensitivity of this biosensor is related to the full width at half maximum (FWHM), FWHM should be discussed. The FWHM can be observed via the electric field distribution.
Figure 2(a) presents the electric field distribution of the TE mode for the resonant wavelength of 798 nm. We can see that the strongest electric field excited in the waveguide layer is 5times greater than that in the weakest part of the field. When the resonant wavelength shifts 10 nm, which is from 798 nm to 788 nm or 808 nm, the electric field distributions are shown in Figure 2(b,c), respectively, which still show a strong guided-mode resonance effect where the strongest part is 4 to 3.5 times greater than the weakest part of the field. With Entinostat the wavelength changed by 20 nm to 778 nm and 818 nm, the electric field distributions are shown in Figure 2(d,e), respectively. However, the GMR effect is very weak. In particular, at the wavelength of 818 nm in Figure 2(e), it is difficult to discern any guided-mode resonance effect.
Figure 2.Electric field distribution of TE mode at different wavelengths. (a) Electric field distribution selleck chemicals Crenolanib at the wavelength of 798 nm with TE mode incident into the GMRF. (b) Wavelength at 788 nm. (c) Wavelength at 808 nm. (d) Wavelength at 778 nm. (e) Wavelength …In contrast, when illuminated with incident light in the TM mode, the electric field distribution calculated by the RCWA method is shown in Figure 3.Figure 3.Electric field distribution of TM mode at different wavelengths.

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