About the Cover:
The image illustrates the collective optical properties of semiconductor perovskite nanocrystals under the excitation of upper blue laser ray. The cubic perovskite nanocrystals exhibit amplified spontaneous emission (ASE) tunable from near UV to near Infrared on the right side. Three sequential bright dots and decaying sinusoidal wave on the lower side represent single photon emission and quantum coherence in perovskite nanocrystals, respectively. Meanwhile, the discrete energy levels and photoluminescence spectrum on the left side correspond to the fine structure of perovskite nanocrystals.
Editorials
Laser: sixty years of advancement
Xiao-Cong (Larry) Yuan and Anatoly Zayats
Vol. 2, Issue 5, 050101 (2020)
News and Commentaries
Reviews
Optical studies of semiconductor perovskite nanocrystals for classical optoelectronic applications and quantum information technologies: a review 
Zengle Cao, Fengrui Hu, Chunfeng Zhang, Shining Zhu, Min Xiao, and Xiaoyong Wang
Vol. 2, Issue 5, 054001 (2020)
Letters
Near-perfect microlenses based on graphene microbubbles
Han Lin, Scott Fraser, Minghui Hong, Manish Chhowalla, Dan Li, and Baohua Jia
Vol. 2, Issue 5, 055001 (2020)
Research Articles
Experimental observation of effective gravity and two-time physics in ferrofluid-based hyperbolic metamaterials
Vera N. Smolyaninova, John Cartelli, Bryan Augstein, Stephanie Spickard, Mary S. Devadas, and Igor I. Smolyaninov
Vol. 2, Issue 5, 056001 (2020)
High-spatial-resolution ultrafast framing imaging at 15 trillion frames per second by optical parametric amplification
Xuanke Zeng, Shuiqin Zheng, Yi Cai, Qinggang Lin, Jinyang Liang, Xiaowei Lu, Jingzhen Li, Weixin Xie, and Shixiang Xu
Vol. 2, Issue 5, 056002 (2020)
Memory effects in scattering from accelerating bodies
Vitali Kozlov, Sergei Kosulnikov, Dmytro Vovchuk, and Pavel Ginzburg
Vol. 2, Issue 5, 056003 (2020)
Reversible switching of electromagnetically induced transparency in phase change metasurfaces
Libang Mao, Yang Li, Guixin Li, Shuang Zhang, and Tun Cao
Vol. 2, Issue 5, 056004 (2020)
Single-mode output by controlling the spatiotemporal nonlinearities in mode-locked femtosecond multimode fiber lasers
Uğur Teğin, Babak Rahmani, Eirini Kakkava, Demetri Psaltis, and Christophe Moser
Vol. 2, Issue 5, 056005 (2020)
