High-energy side-peak emission of exciton-polariton condensates in high density regime

Tomoyuki Horikiri, Makoto Yamaguchi, Kenji Kamide, Yasuhiro Matsuo, Tim Byrnes, Natsuko Ishida, Andreas Löffler, Sven Hoefling, Yutaka Shikano, Tetsuo Ogawa, Alfred Forchel, Yoshihisa Yamamoto

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates -- sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity -- have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.
Original languageEnglish
Article number25655
Number of pages11
JournalScientific Reports
Early online date19 May 2016
Publication statusE-pub ahead of print - 19 May 2016


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