Femtosecond laser filamentation is a unique nonlinear optical phenomenon when high-
power ultrafast laser propagation in all transparent optical media. During filamentation in the …

Recent studies have demonstrated that femtosecond laser pulses have high potential in
application to environmental science. Because of the properties of ultrafast, broadband and …

We propose a new mechanism to explain the origin of optical gain in the transitions between
the excited and ground states of the ionized nitrogen molecule following irradiation of …

We report on the lasing in air and pure nitrogen gas pumped by a single 800 nm
femtosecond laser pulse. Depending on gas pressure, incident laser power and beam …

We report on strong backward stimulated emission at 337 nm in nitrogen gas pumped by
circularly polarized femtosecond laser pulses at 800 nm. A distinct dependence of the …

Filamentation of ultra-short TW-class lasers recently opened new perspectives in
atmospheric research. Laser filaments are self-sustained light structures of 0.1–1 mm in …

We show that the intensity of self-seeded N 2+ lasing at 391 nm, assigned to the B 2 Σ
u+(v′= 0)→ X 2 Σ g+(v′′= 0) emission, is enhanced by 2 orders of magnitude by …

We investigate lasing of a N 2 gas induced by intense few-cycle near-IR laser pulses. By the
pump-probe measurements, we reveal that the intensity of the B Σ 2 u+− X Σ 2 g+ lasing …

Air lasing refers to the remote optical pum** of the constituents of ambient air that results
in a directional laserlike emission from the pumped region. Intense current investigations of …

Nitrogen molecules in ambient air exposed to an intense near-infrared femtosecond laser
pulse give rise to cavity-free superradiant emission at 391.4 and 427.8 nm. An unexpected …