Christopoulos S, von Högersthal G Baldassarri Höger, Grundy A J D, Lagoudakis P G, Kavokin A V, Baumberg J J, Christmann G, Butté R, Feltin E, Carlin J-F, Grandjean N
School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
Phys Rev Lett. 2007 Mar 23;98(12):126405. doi: 10.1103/PhysRevLett.98.126405. Epub 2007 Mar 21.
We observe a room-temperature low-threshold transition to a coherent polariton state in bulk GaN microcavities in the strong-coupling regime. Nonresonant pulsed optical pumping produces rapid thermalization and yields a clear emission threshold of 1 mW, corresponding to an absorbed energy density of 29 microJ cm-2, 1 order of magnitude smaller than the best optically pumped (In,Ga)N quantum-well surface-emitting lasers (VCSELs). Angular and spectrally resolved luminescence show that the polariton emission is beamed in the normal direction with an angular width of +/-5 degrees and spatial size around 5 microm.
我们观察到，在强耦合 regime 下的块状 GaN 微腔中，室温下会发生低阈值跃迁到相干极化激元态的现象。非共振脉冲光泵浦会产生快速热化，并产生清晰的 1 mW 发射阈值，这对应于 29 μJ cm-2 的吸收能量密度，比最佳光泵浦的（In，Ga）N 量子阱表面发射激光器（VCSEL）小 1 个数量级。角度和光谱分辨发光表明，极化激元发射沿法线方向呈束状，角宽度为±5 度，空间尺寸约为 5 微米。
