## 3 Results and Discussion
### Influence of Excitation
Next, we calculated the LCP and RCP light emission by averaging all dipole positions and orientations with this additional weight factor from the passive simulations, thus accounting for the excitation electric field intensity at the position of the dipoles. To demonstrate strong influence of the excitation on both intensity and chirality of emission, we investigated how light emitted at \(\lambda_{em}=940\) nm depends on the excitation wavelengths \(\lambda_{exc}=532\) nm and \(\lambda_{exc}=740\) nm, and on the choice of RCP and LCP, as shown in Figure 8. Since the results are plotted with the same color bar, we note a strong enhancement in the case of LCP excitation at 740 nm. This is a consequence of the high field confinement at the position of the dipole ensemble, as seen in Figure 7b. The emission intensities are \(\sim\)5 times lower for the excitation at 532 nm, compared to 740 nm, while the resulting emitted field distribution shows distinguishable behavior. Namely, at 532 nm excitation, we notice a slight enhancement of both \(\tilde{\Pi}_{\text{LCP}}\) and \(\tilde{\Pi}_{\text{RCP}}\) when its handedness is switched from RCP to LCP, as seen in Figure 8a. At 740 nm excitation, the LCP and RCP emitted components drastically change in distribution and increase in intensity from the excitation change from RCP to LCP, as seen in Figure 8b. This is because the Au-ENHA is strongly chiral at this excitation wavelength, with a pronounced change of the electromagnetic confinement over the ensemble (see the xy cross-sections in Figure 7b). Finally, Figure 9 plots the resulting chiral emission properties for different combinations of the excitation and emission wavelengths, and excitation handedness. We first investigated Au-ENHA, with \(a=500\) nm. In the left panel of Figure 9, we show the CD\({}_{\text{em}}\) calculated from the maps in Figure 8a; we notice that even a slight change of the excitation field distribution (by changing it handedness) can influence the overall map. CD\({}_{\text{em}}\) is rather low close to the normal incidence, but increases in the far-field points which do not have high emission intensity. Therefore, such a configuration is not suitable for excitation. Moving to \(\lambda_{exc}=740\) nm, which strongly couples to the Au-ENHA, the emitted intensity increases and the emission becomes highly tunable by means of excitation (Figure 8b). Figure 7: Passive simulations of the electric field intensity enhancement for the Au-ENHA, when its excited with RCP (top), or LCP (light) from the bottom. We plot normalized electric field intensity in two-unit cell cross-sections, detected by xz-monitor (centered at \(y=0\) nm), and xy-monitor (situated at z = 120 nm), at (**a**) 532 nm, and (**b**) 740 nm. Indeed, in the middle panel of Figure 9, the maximum absolute value of CD\({}_{\rm em}\) increases from 30% in Figure 6, to 50%. As expected, chirality at the excitation wavelength plays an important role in tailoring the CD\({}_{\rm em}\): it increases in absolute value for LCP excitation, and it switched the sign for angles close to normal incidence. Finally, we consider a combination which could be of interest for the ENHA coupled with Styryl 8 dye, which emits around 740 nm, and which can be excited at 633 nm [30,31]. In the right panel of Figure 9, we see that an absolute CD\({}_{\rm em}\) of \(\sim\)20% can be obtained at in the center of the far-field for the LCP excitation. Next, we considered Ag-ENHA with \(a=510\) nm, coupled with a fluorescent ensemble excited at 532 nm and emitting at 630 nm. We choose these wavelengths as they can be of interest for Lumogen Red dye, which has the typical absorption and emission spectra shown in Figure 10a [45]. In this case, both the excitation and emission wavelengths lie in the positive CD\({}_{\rm A}\) branch of our nanostructure (Figure 2f). In the inset of Figure 10b, we show the normalized electric intensity over the xy cross-section at 120 nm. Compared to the Au-ENHA (Figure 7a), RCP and LCP distribution strongly differed.