Direct observation of exceptional points in coupled photonic-crystal lasers with asymmetric optical gains.
Direct observation of exceptional points in coupled photonic-crystal lasers with asymmetric optical gains.
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直接观察具有不对称光学增益的耦合光子晶体激光器中的异常点。
DOI：
10.1038/ncomms13893
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发表时间：
2016-12-21
影响因子：
16.6
通讯作者：
中科院分区：
文献类型：
--
作者：
尽管在基于微米级腔的非厄米光学系统中观察到了与直觉相反的特征，但实现简单但明确的方法以实现例外点(EP)的有效访问和向所需激光模式的相变仍然是一个挑战，特别是在波长尺度耦合腔中。在这里，我们展示了具有非对称光学增益的耦合光子晶体(PHC)纳米激光器，并通过调节一个PHC腔上的石墨烯覆盖面积和系统的扫描光致发光测量，观察到EPs处激光模式的相变。当两个相同的PHC腔之间的增益对比度超过腔间耦合时，发生了从键合/反键激光模到单放大激光模的相变，这一点被模像的实验测量和非对称增益耦合腔的理论模型所证实。此外，我们还展示了通过电选通控制石墨烯的光学损耗来实现EPs的主动调谐。当非厄米光学系统从PT对称到PT对称破缺时，已经被证明能够维持激光。在这里，Kim等人。研究了部分覆盖石墨烯的耦合微腔中激光模式的这种相变，并显示了一个例外点的调谐。
Although counter-intuitive features have been observed in non-Hermitian optical systems based on micrometre-sized cavities, the achievement of a simplified but unambiguous approach to enable the efficient access of exceptional points (EPs) and the phase transition to desired lasing modes remains a challenge, particularly in wavelength-scale coupled cavities. Here, we demonstrate coupled photonic-crystal (PhC) nanolasers with asymmetric optical gains, and observe the phase transition of lasing modes at EPs through tuning of the area of graphene cover on one PhC cavity and systematic scanning photoluminescence measurements. As the gain contrast between the two identical PhC cavities exceeds the intercavity coupling, the phase transition occurs from the bonding/anti-bonding lasing modes to the single-amplifying lasing mode, which is confirmed by the experimental measurement of the mode images and the theoretical modelling of coupled cavities with asymmetric gains. In addition, we demonstrate active tuning of EPs by controlling the optical loss of graphene through electrical gating. Non-Hermitian optical systems have been shown to sustain lasing when they go from a PT-symmetric to a PT-symmetry-broken phase. Here, Kim et al. study this phase transition of lasing modes in partially graphene-covered coupled microcavities and show tuning of an exceptional point.
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影响因子：
8.6
作者：
Bender, CM;Boettcher, S
通讯作者：
Boettcher, S
影响因子：
10.8
作者：
Gan, Xuetao;Mak, Kin Fai;Englund, Dirk
通讯作者：
Englund, Dirk
影响因子：
4
作者：
Brunstein, M.;Karle, T. J.;Yacomotti, A. M.
通讯作者：
Yacomotti, A. M.
影响因子：
56.9
作者：
Park, HG;Kim, SH;Lee, YH
通讯作者：
Lee, YH
影响因子：
10.8
作者：
Gao, Yuanda;Shiue, Ren-Jye;Englund, Dirk
通讯作者：
Englund, Dirk