Subterawatt few-cycle mid-infrared pulses from a single filament

Octave-spanning single-cycle middle-infrared generation through optical parametric amplification in LiGaS2

“…Direct broadband laser sources are rare in the MIR due to lack of suitable materials. Researchers are therefore invoking nonlinear optical conversions, for example difference frequency generation or optical rectification in nonlinear crystals [10][11][12][13] such as GaSe or AgGaS 2 [14,15], filaments [16,17] or plasmas [18]. A quite new material is LiGaS 2 (LGS) [19][20][21][22][23][24] which offers a broadband transparency range (0.32-11.6 µm) and a large bandgap of ∼4 eV that leads to very weak two-photon absorption for Ti:sapphire-based (∼800 nm) or Yb-based (∼1030 nm) laser pulses.…”

Relativistic Single-Cycle Tunable Infrared Pulses Generated from a Tailored Plasma Density Structure

“…Some other methods, such as difference frequency generation (DFG) [19], adiabatic DFG [20], non-degenerate four-wave-mixing [21][22][23] and optical rectification [24][25][26], have attained microjoule level pulse energy, not sufficient for strong-field applications. There are also some post-processing methods, such as post compression [27,28] or synthesis [29], that are often more complex than direct generation methods. In other words, the generation of coherent, ultra-intense IR pulses is still an outstanding problem.…”

Keldysh photoionization theory: through the barriers

“…As can be seen from these simulations, with the electron density increasing from the leading edge of the pulse to its trailing edge, different sections of the beam undergo different dynamics. This difference is due to the buildup of the electron density within the laser pulse [244,245]. The leading edge of the pulse induces ionization of the air, giving rise to a transverse profile of the electron density, falling off from the center of the beam to its periphery.…”