title: Second thresholds in BEC-BCS-laser crossover of exciton-polariton systems.
abstract: The mechanism of second thresholds observed in several experiments is theoretically revealed by studying the BEC-BCS-laser crossover in exciton-polariton systems. We find that there are two different types of second thresholds: one is a crossover within quasiequilibrium phases and the other is into nonequilibrium (lasing). In both cases, the light-induced band renormalization causes gaps in the conduction and valence bands, which indicates the existence of bound electron-hole pairs in contrast to earlier expectations. We also show that these two types can be distinguished by the gain spectra.
authors.affiliation: Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. yamaguchi@acty.phys.sci.osaka-u.ac.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Kenji
authors.initials: K
authors.lastname: Kamide
authors.forename: Ryota
authors.initials: R
authors.lastname: Nii
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ogawa
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamamoto