2026-10-12T03:28:43Z https://www.scidb.cn/oai

10.57760/sciencedb.40875 2026-06-29T15:24:39Z

2026-06-29 Low-threshold efficient N2+ lasing driven by sub-cycle soliton dynamics in a hollow waveguide doi:10.57760/sciencedb.40875 en Controlling the quantum-state populations of microscopic system on the few- or sub-cycle timescale engages light–matter interaction at its most fundamental level, offering unique opportunities to realize new physical processes and to create advanced light sources. Here, we demonstrate population dynamics in nitrogen molecular ions (N2+) driven by sub-cycle soliton dynamics. High-order-soliton compression of a 12-fs, 10-μJ-level pump pulse in a N2-filled tapered hollow capillary forms a sub-cycle asymmetric transient that tunnel-ionizes N2 to N2+ and, through direct single-photon resonant excitation, creates population inversion between the ground X2Σg+ state and the excited B2Σu+ state—a process distinct from the widely adopted three-state coupling picture—at unexpectedly low pump energy. Experimentally, we obtain 100-nJ-level N2+ lasing pulses at 391 nm with conversion efficiencies up to 3.3 × 10-3 and pump energies below 50 μJ, improving both efficiency and threshold by more than one order of magnitude over prevailing filamentation-based schemes. Our results establish sub-cycle manipulation of ionic populations as a powerful approach that bridges two largely separate fields (sub-cycle soliton dynamics and N2+ lasing), and paves the way for narrow-band, high-beam-quality lasing pulses that may find wide applications in advanced spectroscopy and nonlinear pump-probe experiments. air lasing; soliton dynamics; hollow core fibres Tiandao Chen RESTRICTED dataset Science Data Bank