Laser filamentation is one of the "nonlinear magic" effects that show up as part of complex nonlinear dynamics observed for an ultrashort powerful electromagnetic field waveform propagating in a gas, liquid, or solid material. The physics behind this magic involves a combination of nonlinear-optical phenomena that suppress diffraction-induced beam divergence, giving rise to a long radiation channel—a laser filament—whereby electromagnetic fields and their energy can be transmitted over large distances. Filaments of long-wavelength infrared (LWIR) radiation are of special interest because the atmosphere has suitable transparency windows in the LWIR range and because longer-wavelength filaments can accommodate higher radiation powers. At the current stage of laser technologies, however, adequately high laser peak powers can only be delivered in the LWIR range in the form of picosecond pulses. Such pulses are prone to a temporal splitting as they propagate through the atmosphere. This effect is highly detrimental for laser filamentation. Now, Panagiotopoulos and coauthors have identified a much-needed method that can help prevent this unwanted splitting of high-power LWIR pulses. They demonstrate, by a masterful analytical work and elegant simulations, that picosecond pulse sequences can be carefully tailored to enable an efficient control over filamentation dynamics, providing high-quality spatio-temporal field profiles at the output of LWIR filaments in the atmosphere. This important discovery opens new horizons in remote sensing, long-range communications, and long-distance delivery of powerful laser radiation.
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