In article number 1800306, Zhijie Wang, Peng Jin, Shengchun Qu, and co-workers construct plasmonic lasers based on the structure of metal/dielectric layer/perovskite nanowires via an electrochemically assisted growth method for the high-quality perovskite nanowires. The plasmonic lasers demonstrate a threshold of 62 µJ cm⁻², a high quality factor of Q = 655, and a fast lasing decay time of 1.6 ps. The purple light represents the pumping input energy; the green-light emission of the plasmonic laser is mainly constrained to the dielectric layer; the variations of the green spectra indicate the possibility of mode modulation of perovskite-nanowire-based plasmonic lasers.

In article number 1900079, Shumin Xiao, Qinghai Song, and co-workers demonstrate a perovskite metasurface at the working wavelength of 632 nm, displaying high-efficiency polarization conversion, anomalous reflection, and meta-holograms. The bandgap of the perovskite can be post-synthetically and reversibly tuned via anion exchange. For the holograms, reflected light is imaged on a screen, where the experimental results of “ON” and “OFF” are displayed simultaneously. The designed devices should have future applications in the semiconductor field.

Saturable absorption induced by Pauli-blocking allows intense light to pass while low-intensity light is absorbed. This can be utilized for mode-locking to generate ultrashort laser pulses. Saturable absorption in a wide range of 2D nanomaterials and related photonic devices is reviewed, together with its applications in mode-locked lasers, using slow- and fast-saturable absorption models.

A water-immersible 90-m-long fully-integrated fiber system is constructed, which allows distributed quantum magnetic sensing over large distances with a sensitivity of 63 nT Hz^−1/2. The fiber contains hundreds of embedded photodiodes connected in parallel and a hollow optical waveguide that contains a fluid with nitrogen-vacancy diamonds. Applications include remote detection of ferrous metals, geophysics, and biosensing.

Plasmonic lasers based on the structure of metal/dielectric layer/perovskite nanowires are constructed via an electrochemical-assisted growth method for high-quality perovskite nanowires. The plasmonic lasers demonstrate a threshold of 62 µJ cm⁻², a high quality factor of ≈655, and a fast lasing decay time of 1.6 ps. The laser modes can be effectively manipulated by adjusting the pump energy.

The first phosphorescence-amplified spontaneous emission in solution from a pure organic luminescent rotor is demonstrated. Furthermore, modulation of ASEs between singlet fluorescence and triplet phosphorescence channels is achieved by adjusting the relative rotation of the donor and acceptor moieties. Methyl is added in the molecule to increase the steric hindrance, leading to tunable phosphorescence or fluorescence dye ASEs.

By combining digital signal processing and nonlinear optical processes, the concept of nonlinear coding metasurfaces is proposed, which has great superiority in the implementation of highly integrated and multifunctional devices. Based on this concise and flexible methodology, a multifocal metalens and a multifunctional metasurface are encoded and demonstrated by both numerical calculations and experiments.

A giant enhancement of third-harmonic generation (THG) efficiency from an air/Ge₂Sb₂Te₅ (GST)/gold multi-layered Fabry–Perot cavity is presented. Interestingly, the THG efficiency has a dramatic decrease of three orders when the structural state of GST transforms from amorphous to crystalline. These findings have a potential for achieving an ultracompact nonlinear optical source with high efficiency and switchable functionality.

MAPbX₃-perovskite-based metasurfaces are experimentally demonstrated with a complete control of phase shift. High-efficiency polarization conversion, anomalous reflection, and meta-holograms are successfully produced. Most interestingly, the bandgap of the perovskite can be post-synthetically and reversibly tuned via anion exchange, providing a new approach to dynamically control the all-dielectric meta-devices with novel function.