Air lasing from single ionized N 2+ molecules induced by laser filamentation in air has been
intensively investigated and the mechanisms responsible for lasing are currently highly …

In standard lasers, light amplification requires population inversion between an upper and a
lower state to break the reciprocity between absorption and stimulated emission. However …

Harnessing structured light is fascinating for its multidisciplinary applications, eg, in remote
driving microrobots, sensing, communications, and ultrahigh resolution imaging. Here, we …

Nitrogen molecules pumped by intense femtosecond laser pulses give rise to coherent
emission in the forward direction at a series of wavelengths, coined “air lasing.” We …

The first solid-state masers to operate at room-temperature and ambient air-pressure were
recently demonstrated using optically pumped spin-triplet states as the gain medium. In this …

A near-infrared femtosecond laser pulse produces laserlike coherent radiation from singly
ionized N 2+ molecules when it experiences filamentation in air or pure nitrogen, and the …

We experimentally investigated the rotationally resolved polarization characteristics of N 2+
lasing at 391 and 428 nm using a pump-seed scheme. By varying the relative angle …

We investigated ultrashort pulse filamentation and lasing action of N2+ for pump-probe
experiments in gases. Using femtosecond coherent anti-Stokes Raman scattering, the white …

Superfluorescence emission around 391 nm is generated when nitrogen molecules are
irradiated by a strong 800-nm pump laser and a delayed seed laser. The emission …

The processes leading to the N_2^+ lasing are rather complex and even the population
distribution after the pump laser excitation is unknown. In this paper, we study the population …