Enhancement of high-order harmonic generation using a two-color pump in plasma plumes

Harmonic generation in laser-produced plasmas containing atoms, ions and clusters: a review

“…The two-colour pump using the fundamental and second-harmonic (SH) fields has become a practical way of harmonic enhancement in gas media [115][116][117][118][119][120][121]. The same approach has recently been reported for plasma harmonics when the enhanced HHG in laser-produced plasma plumes was observed using a two-colour laser pump (98% of 800 nm and 2% of 400 nm [58] and 92% of 800 nm and 8% of 400 nm [59]). The use of a plasma plume as the HHG medium in the two-colour pump scheme allows for the search of appropriate targets where the resonance enhancement can be achieved for the even harmonics of a Ti:sapphire laser, analogous to previously reported observations of resonantly enhanced odd harmonics in the case of the single pump scheme [63,65].…”

“…Among them are the studies of harmonics from clusters using the ablation of commercially available nanoparticles [42,43], fullerenes [44][45][46] and carbon nanotubes [47], resonanceenhanced features of odd and even harmonics [48], generation of extremely broadband high-order harmonics [49], application of high pulse repetition rate laser sources and ultrashort pulses for HHG in plasma plumes [32], observation of quantum path signatures in the harmonic spectra from various plasmas [33], enhancement of harmonics from in situ-produced clusters [50], development of few theoretical approaches describing the observed peculiarities of resonance-enhanced harmonics [51][52][53][54][55][56], emergence of a 'second' plateau in the harmonic distribution [57], development of the two-colour pump schemes for plasma-induced harmonics [58,59], observation of extremely strong HHG in carbon-contained plasmas [39,40], proposals for the quasi-phase matching in plasma plumes [60], observation of the attosecond nature of pulse duration of the plasma-induced harmonics [61], etc. Most of these findings will be discussed in the present review.…”

Perturbation-theory analysis of ionization by a chirped few-cycle attosecond pulse

“…In the IR frequency domain short, chirped pulses have already been used in a number of applications, such as to control the populations of molecular vibrational and rotational states (see, e.g., Refs. [13][14][15][16][17][18]), to control ultracold atomic collisions [19], to control population transfer in few-level model atoms [20][21][22][23], to control the extent of the plateau cutoffs for both HHG [24,25] and above-threshold ionization (ATI) [26], to control the HHG process in order to produce single attosecond pulses [27], and to increase the intensity of the HHG spectrum using a two-color pump scheme [28]. Both ATI [29] and multiphoton ionization [30,31] by a short, chirped IR pulse have been found to be sensitive to the chirp of the pulse.…”

Time-resolved spectroscopy of plasma plumes: A versatile approach for optimization of high-order harmonic generation in laser plasma

“…This intensity range was defined from previous studies of the HHG in laser plumes. [10][11][12] The second (femtosecond) pulse was focused by a 50-cm focal length lens inside the plasma from the direction orthogonal to the heating pulse propagation after some delay with regard to the heating (210 ps) pulse. We analyzed plasma emission both with and without the influence of femtosecond (t ¼ 35 fs) pulse on plasma dynamics.…”