Superfluorescence from photoexcited semiconductor quantum wells: Magnetic field, temperature, and excitation power dependence

Abstract

Superfluorescence (SF) is a many-body process in which a macroscopic polarization spontaneously builds up from an initially incoherent ensemble of excited dipoles and then cooperatively decays, producing a delayed pulse of coherent radiation. SF arising from electron-hole recombination has recently been observed in In0.2Ga0.8As/GaAs quantum wells [G. T. Noe et al. Nat. Phys. 8, 219 (2012) and J.-H. Kim et al. Sci. Rep. 3, 3283 (2013)], but its observability conditions have not been fully established. Here, by performing magnetic field (B), temperature (T ), and pump power (P ) dependent studies of SF intensity, linewidth, and delay time through time-integrated and timeresolved magneto-photoluminescence spectroscopy, we have mapped out the B-T -P region in which SF is observable. In general, SF can be observed only at sufficiently low temperatures, sufficiently high magnetic fields, and sufficiently high laser powers with characteristic threshold behavior. We provide theoretical insights into these behaviors based primarily on considerations on how the growth rate of macroscopic coherence depends on these parameters. These results provide fundamental new insight into electron-hole SF, highlighting the importance of Coulomb interactions among photogenerated carriers as well as various scattering processes that are absent in SF phenomena in atomic and molecular systems.

Dicke superradiance in solids [Invited]

“…Figures 20(a)-20(f) demonstrate that increasing T has an effect similar to decreasing B on the delay time of SF emission [141]. These data were taken at 10 ing T , the intensity of SF gradually decreases, and finally, at T > 150 K, no SF bursts can be observed.…”

“…Figures 20(a)-20(f) demonstrate that increasing T has an effect similar to decreasing B on the delay time of SF emission [141]. These data were taken at 10 T and 2 mW at T = (a) 4 K, (b) 50 K, (c) 75 K, (d) 100 K, (e) 125 K, and (f) 150 K. At each T , multiple SF bursts coming from different LLs can be seen, with delay times that are shorter for those arising from higher LLs.…”

“…TIPL showed very different behaviors between the center and edge collections. Figures 13(a) and 13(b) show the B dependence of time-integrated center-fiber and edge-fiber-collected PL, respectively, from B = 0 T to 10 T with P = 2 mW and at T = 4 K [141]. The only feature observed in the center-fiber-collected PL, shown in Fig.…”

“…Spontaneous emission (SE) is emitted isotropically, while SF is emitted in the QW plane and detected through the edge fiber. Reproduced (adapted) with permission from [141]. Copyright 2015, American Physical Society.…”

“…12. Two fibers, center and edge fibers, were used for PL collection; the former was used for monitoring spontaneous emission (which was emitted in all 4π spatial directions with equal probability), while the latter was used to observe SF (which was emitted in the plane of the QWs) [56,140,141,143]. TIPL was measured with a CCD-equipped monochromator, and TRPL was measured either using a streak camera system or a Kerrgate method.…”