Figure 1

(Color online) (a) Schematic view of the setup. Laser light is coupled into the SNOM tip and excites the sample. The photoluminescence of the infiltrated QDs is collected through the same tip, dispersed in a monochromator, and detected with a cooled InGaAs diode array. Inset (I): SEM image of the photonic crystal microcavity. (b) Typical photoluminescence spectrum of QDs infiltrated inside the structures (black line) compared with the spectrum of the same QDs outside the cavity (gray line). The dotted lines represent the positions of the calculated modes using the guided-mode expansion method of the structure without including the presence of the QD solution inside the central hole. The calculated main mode of the cavity at $1315\mathrm{nm}$ is observed in the experimental spectrum, while the modes around $1200\mathrm{nm}$ are not observed since they do not couple with the near-field probe in the specific point of the sample where the spectrum is taken.Reuse & Permissions

Figure 2

Near-field spectra collected for different positions as indicated in the shear force topographic image $(2\times 2\mu {\mathrm{m}}^2)$ reported in (I).Reuse & Permissions

Figure 3

Near-field spectra related to two infiltrations performed on different samples with the same nominal parameters. If a not perfect infiltration is performed, we obtain a reduction of the $Q$ factor by a factor of 4. In the insets the topography images of the samples for the two different infiltrations are reported; in particular inset (I) presents the topography image $(2\times 2\mu {\mathrm{m}}^2)$ of the sample surface obtained in correspondence with the spectrum in gray line, while inset (II) corresponds to the spectrum in black line.Reuse & Permissions

Figure 4

(Color online) (a),(b) Measured spatial intensity distribution associated to the cavity peak at $1315\mathrm{nm}$ and to the broader peak at $1257\mathrm{nm}$, respectively. (c),(d) Calculated intensity distributions of the electric field component along the $x$ axis [size of images (a) and (d) $2\times 2\mu {\mathrm{m}}^2$]. (e), The experimental spectrum obtained integrating all over the image (black line) is compared with the calculated spectrum of the intensity associated with the electric field component along the $x$ axis (red line) over the same scanning region at distance $d=1.36\mu \mathrm{m}$. (f) Distribution of the intensity of the electric field component along the $x$ axis collected in a vertical plane along the $y$ direction and centered in the middle of the cavity (image size $2.3\times 3\mu {\mathrm{m}}^2$). The white dotted line represents the effective height in which the simulated profile of the electric field (yellow dotted line) is collected. The yellow solid lines represent the normalized experimental profile of the cavity mode.Reuse & Permissions