We experimentally demonstrate the existence of long-lived coherent polarizations coupling simultaneously ground state X (X2Σg+) to excited states A (A2Πu) and B (B2Σu+) of N2+ inside a plasma created by a short intense laser pulse at 800 nm. This three-level V-scheme arrangement is responsible for a strong optical gain without population inversion at the B–X transition at 391.4 nm. Simulations based on Maxwell-Bloch equations reproduce well the kinetics and the pressure dependence of the gain.

Optical and magnetic responsive deforming multilayered films with rapid deforming recovery property were successfully fabricated by electrospinning technology. Polyvinyl alcohol (PVA)/liquid crystal (LC) 5CB (4‐cyano‐4'pentylbiphenyl)/graphite fiber film was orderly collected on the thermoplastic polyurethanes (TPU) substrate film by parallel electrode electrospinning method. Graphite and nano‐magnetic particles had been added to endue it with optical and magnetic responsibility. Evaluated by a customized 3D‐printed platform, the deforming multilayered film shows its high deforming recovery speed. Therefore, the proposed deforming multilayered films can be applied in the field of bionic control with the advantage of rapid optical and magnetic responsibility, nontoxicity, and simple fabrication approach. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46884.

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Lasing of [Formula: see text] at 428 nm is studied as a function of the delay dt between two 800 nm ultrashort pumping pulses from a Ti:sapphire laser. This lasing corresponds to a population-inverted transition between levels [Formula: see text](0) and [Formula: see text](1) of a singly ionized nitrogen molecule. An important erasing of laser emission is observed under pumping with two consecutive pulses separated by large delays −20 ps < dt < +20 ps. From an analysis of the quenching results, we conclude that the mechanism of lasing corresponds to a coherent two-photon amplification scheme. Our results show that a two-photon process can dominate over a population-inverted one-photon amplification.