Inhibited spontaneous emission using gaplike resonance in disordered photonic structures

We study the mesoscopic light transport and emission dynamics in a photonic structure made up of monodisperse scatterers as it undergoes an order-disorder structural transition. We have found a prominent tunable gaplike resonance in samples with 100% induced disorder due to the formation of clusters which consist of scatterers with short-range order. The wavelength-dependent decay rate for an emitter embedded inside the photonic structure at different levels of induced disorder is investigated. Surprisingly, the sample with 100% induced disorder exhibits comparable emission rates with 0% induced-disorder sample which indicates a similar local density of photon states (LDOS) variations in both limits of the disorder. The results are interpreted as the effect of LDOS suppression on the emission of light caused by the gaplike resonance which is in accordance with the theory.

Figure 1

(a)–(c) SEM images of $S_1, S_3$, and $S_6$ samples indicate the growth of induced disorder along with visual impressions of $S_1$ and $S_6$ samples in the inset. (d) The variation of reflectivity (closed circles) and transmittance (open circles) values at 600 nm as function of increase in electrolyte concentration. The inset shows the variation in $l_{\mathrm{s}}$ values with increase in induced disorder at 600 nm. (e), (f) The measured total transmittance (reflectivity) spectra indicate stop gap which appears as a dip (peak) at 600 nm for $S_1$ (dotted) sample. The stop gap is wiped out with an increase in transmittance values for $S_3$ (dashed-dotted) sample. A sudden decrease in transmittance is observed for $S_6$ (dashed) sample with a shallow dip near 600 nm along with dye absorption band at 545 nm. (g) The total reflectivity (solid) and total transmittance (dashed) spectra for 100% induced-disorder sample made up of nondyed spheres. (h) The diffuse intensity (squares) and total diffuse intensity (circles) values at 600 nm show a linear increase with decrease in $l_{\mathrm{s}}$. The total diffuse intensity value shows a prominent decrease for $S_6$ sample.

Figure 2

(a)–(d) The measured (symbols) and fitted (solid line) decay curves at 570 nm (top panel) and 600 nm (bottom panel) for sample $S_3$ (squares) and $S_6$ (diamonds) that are compared with sample $S_1$ (circles). The $S_3$ sample presents a faster decay leading to less $\langle \tau \rangle$ value as compared to the $S_1$ sample. However, the measured $\langle \tau \rangle$ values for the $S_6$ sample are higher than that of the $S_1$ sample and are incongruous to the decay curves as shown in (b) and (d). The $\langle \tau \rangle$ value for $S_6$ sample is comparable to $S_1$ sample depicting the suppression of LDOS at 600 nm.

Figure 3

(a) The wavelength dispersion of the estimated lifetimes for $S_1$ (circles), $S_3$ (squares), and $S_6$ (diamonds) samples. The specular reflectivity spectra (solid line) for the $S_1$ sample depict the stop-gap wavelength range. (b) The variation of $\langle \tau \rangle$ values as a function of $l_{\mathrm{s}}$ at 600 nm. The $\langle \tau \rangle$ value first decreases linearly with the decrease in $l_{\mathrm{s}}$ value and then evinces a sudden increase at the lowest $l_{\mathrm{s}}$ value for $S_6$ sample (dashed line is a guide for the eye).

Figure 4

(a)–(f) SEM images taken for $S_1$ to $S_6$ samples, along with FFT (inset), respectively. The growth of induced disorder is seen in the images accompanied with changes in FFT.

Figure 5

(a) The measured specular reflectivity and (b) ballistic transmittance spectra for $S_1$ to $S_6$ samples. At high values of induced disorder, both reflectivity and transmittance show near-zero values at all wavelengths.

Figure 6

(a), (b) Streak images shown for $S_1$ and $S_6$ samples, respectively. (c)–(f) The decay curves are plotted at each wavelength with a spectral width of 4 nm for the $S_1, S_3, S_4$, and $S_6$ samples, respectively.

Figure 7

The decay curves are shown for $S_1$ (circles), $S_3$ (downward triangles), $S_4$ (upward triangles), and $S_6$ (diamonds) samples at (a) 570 and (b) 600 nm, respectively.

Figure 8

The simulated decay curves at 570 nm (a), (b) and at 600 nm (c), (d) for the $S_1$ (squares), $S_3$ (circles), $S_4$ (upward triangles), and $S_6$ (downward triangles) samples correspond to ${\tau }_1$ and ${\tau }_2$ values in Table 1 and Table 2, respectively. The decay curves simulated for all the samples using ${\tau }_1$ values show a fast nonexponential decay. The decay curves overlap each other at 570 nm and overlap for $S_1$ and $S_4$ samples and $S_3$ and $S_6$ samples at 600 nm. The decay curves simulated for ${\tau }_2$ values clearly depict the fastest decay for the $S_4$ sample at 570 and 600 nm. The slowest decay for the $S_6$ sample is observed at 570 and 600 nm. The decay curves overlap for $S_1$ and $S_6$ samples depicting a slower decay.