Figure 1

(Color online) The energy-radius $(E,r)$ images of the exciton energy versus radius during the time evolution of the exciton inner ring following the onset and termination of the rectangular laser pulse. Time $t=0\text{ns}$ corresponds to the onset of the laser pulse of the duration ${\tau }_{\text{pulse}}=500\text{ns}$. Each image is integrated over a time window of $\delta t=4\text{ns}$ ending at the times [(a)–(c)] $t=4$, 12, and 24 ns after the start of the laser pulse, and [(d)–(f)] $t-{\tau }_{\text{pulse}}=0$, 4, and 68 ns after its termination. The laser is focused to a $10\mu \text{m}$ full width half maximum (FWHM) excitation spot on the CQW sample.Reuse & Permissions

Figure 2

(Color online) Kinetics of the indirect exciton PL profile after the laser-excitation onset. The (a) measured and (b) calculated cross sections of the indirect exciton PL across the diameter of the inner exciton ring as a function of time. The (c) measured and (d) calculated indirect exciton PL intensity at the center of the laser-excitation spot (red ▼) and at the inner ring radius $r=r_{\text{ring}}\simeq 12\mu \text{m}$ (blue ●), where the PL maximum signal occurs, as a function of time. The time-integration window $\delta t=4\text{ns}$ for each profile (a) and (b) and each point (c) and (d). The times $t=0\text{ns}$ and $t=500\text{ns}$ correspond to the onset and termination of the rectangular laser-excitation pulse. The laser-excitation profile is shown by the thin dotted line in (a).Reuse & Permissions

Figure 3

(Color online) Kinetics of the indirect exciton PL profile during the laser-excitation termination. The (a) measured and (b) calculated with Eqs. (1, 2, 3) spatial profiles of the PL signal from indirect excitons across the inner ring at the times $t=500\text{ns}$ (dash-dotted line), 504 ns (dotted line), and 568 ns (solid line). The times $t=0\text{ns}$ and $t=500\text{ns}$ correspond to the onset and termination of the rectangular laser-excitation pulse. The (c) measured and (d) evaluated numerically contrast of the PL jump $\left(I_{\text{max}}-I_{\text{laser}\text{on}}\right)/I_{\text{laser}\text{on}}$ against the radial coordinate. The laser-excitation profile is shown by the dotted line in (c). The (e) measured and (f) calculated indirect exciton PL intensity at the center of the laser excitation spot (red ▼) and at the radial distance where the PL maximum intensity occurs, $r=12\mu \text{m}$, (blue ●) as a function of time. Insets: (d) The contrast of the PL jump and (f) the PL jump at the center of excitation, evaluated with Eqs. (1, 2, 3) without time integration to match 4 ns experimental resolution. Apart from the insets, each calculated curve is smoothed by the device resolution function with the time-integration window $\delta t=4\text{ns}$ to match the experimental conditions.Reuse & Permissions

Figure 4

(Color online) Exciton and electron (hole) concentrations, $n_{\text{x}}$ and $n_{\text{e}}=n_{\text{h}}$, as a function of temperature, evaluated by using the quantum mass action law: $n_{\text{x}}+n_{\text{e}\left(\text{h}\right)}=2\times {10}^{10}{\text{cm}}^{-2}$ (dashed lines), ${10}^{10}{\text{cm}}^{-2}$ (dash-dotted lines), and $0.5\times {10}^{10}{\text{cm}}^{-2}$ (solid lines). The indirect exciton binding energy ${ϵ}_{\text{x}}=3.5\text{meV}$.Reuse & Permissions

Figure 5

(Color online) Modeling of the transient dynamics of the (a) exciton temperature $T$, (b) density $n_{\text{x}}$, (c) optical lifetime ${\tau }_{\text{opt}}$, and (d) in-plane diffusion coefficient $D_{\text{x}}$ for the onset of the laser excitation. The radial coordinate is $r=0$ (solid line), $r_{\text{ring}}/2$ (dotted line), $r_{\text{ring}}$ (dashed line), and $3r_{\text{ring}}/2$ (dash-dotted line).Reuse & Permissions

Figure 6

(Color online) Modeling of the transient dynamics of the (a) exciton temperature $T$, (b) density $n_{\text{x}}$, (c) optical lifetime ${\tau }_{\text{opt}}$, and (d) in-plane diffusion coefficient $D_{\text{x}}$ for the termination of the laser excitation. The radial coordinate is $r=0$ (solid line), $r_{\text{ring}}/2$ (dotted line), $r_{\text{ring}}$ (dashed line), and $3r_{\text{ring}}/2$ (dash-dotted line). Inset: The calculated spatial profile of the exciton temperature, $T=T\left(r\right)$, for $t=500\text{ns}$ (solid line) and $t=504\text{ns}$ (dotted line).Reuse & Permissions