## 3 Results and Discussion
### Influence of Excitation  
Figures 4 and 5 show that dipole position strongly influences chiral emission in CD\({}_{\mathrm{em}}\) and its intensity. An additional way to boost and tune this performance is to add another degree of freedom: electromagnetic confinement at the excitation wavelength. Apart from controlling the emission direction, polarization and intensity, plasmonic nanostructures can boost absorption in the emitting material by controlling its excitation rate \(\gamma_{\mathrm{ab}}\), as \(\gamma_{ab}\sim\left|\overrightarrow{\mu}_{ab}\overset{\rightarrow}{E}_{exc }\right|^{2}\), where \(\overset{\rightarrow}{\mu}_{ab}\) is the absorption dipole moment, and \(\overset{\rightarrow}{E}_{exc}\) is the electric field at the excitation wavelength at the dipole position [40]. Different plasmonic systems have been used to optimize molecule fluorescence by means of near field enhancement at the excitation wavelength [38; 40; 41; 42; 43; 44]. In such systems, excitation field properties such as wavelength, incidence angle, and polarization can be engineered to enhance electromagnetic confinement in the parts of the nanostructure volume filled with the emitting material. Next, we demonstrate the influence of excitation (wavelength and polarization) on the emitting chiral properties of Au-ENHA with \(a\) = 500 nm. We choose to investigate \(\lambda_{exc}\) = 532 nm, which is a common green laser used for the excitation of emitters with plasmonic nanostructures [45], and \(\lambda_{exc}\) = 740 nm, where Au-ENHA shows high CD\({}_{\mathrm{A}}\). As our ENHAs are chiral over a broad spectral range, we expect that the switching of LCP to RCP in the excitation influences emitted field intensity and chirality. We started from the passive behavior of the Au-ENHA at single wavelengths by exciting the ENHA from the bottom (positive z-direction), with RCP or LCP (top and bottom panels of Figure 7, respectively). The electric field intensity at the excitation wavelength \(\left|\overset{\rightarrow}{E}_{exc}\right|^{2}\) was detected by two field-profile monitors over the unit cell in the xz cross-section, centered at y = 0 nm, and in the xy cross-section, centered at z = 120 nm (note that this is the same position as the dipole ensemble in the active simulations). This intensity was normalized to the incident field intensity \(\left|\overset{\rightarrow}{E}_{0}\right|^{2}\), with \(E_{0}\) = 1 V/m. As can be appreciated from Figure 2a,b, at \(\lambda_{exc}\) = 532 nm there was no increased coupling with the ENHA, hence it did not possess chiral behavior in the absorption (green area in Figure 2c). Indeed, Figure 7a shows that for both LCP and RCP excitation, the electric field was not confined to the metallic layer, and  
Figure 6: \(I_{\mathrm{LCP}}\), \(I_{\mathrm{RCP}}\), \(\bar{I}_{\mathrm{tot}}\), and CD\({}_{\mathrm{em}}\) maps for the ensemble of 85 homogeneously distributed randomly oriented dipoles for the Au-ENHA, at 740 nm (**top**), and 940 nm (**bottom**). did not overlap with the emitter position (low confinement across the whole xy-monitor). However, there was a slight difference in its distribution, with the switch of the excitation handedness. On the other side, Figure 7b shows high coupling with the ENHA, which was greatly enhanced for the excitation switching from RCP to LCP. This is in agreement with the strong chirality at this wavelength, as seen in the orange region of Figure 2c. For each of simulations presented in Figure 7, we save the intensities of each field component in the points defined in the inset of Figure 1b. As was expected for the confinement with plasmonic nanohole arrays, the main field component for each excitation was \(E_{z}\) (not shown here); this means that the z-oriented dipoles standing on the nanohole rims will enter the sum in Equation (4), with significantly higher weight.