Fifteen terawatt picosecond CO_2 laser system

Abstract

The generation of a record peak-power of 15 TW (45 J, 3 ps) in a single CO(2) laser beam is reported. Using a master oscillator-power amplifier laser system, it is shown that up to 100 J of energy can be extracted in a train of 3 ps laser pulses separated by 18 ps, a characteristic time of the CO(2) molecule. The bandwidth required for amplifying the short injected laser pulse train in a 2.5 atm final CO(2) amplifier is provided by field broadening of the medium at intensities of up to 140 GW/cm(2). The measured saturation energy for 3 ps pulses is 120 mJ/cm(2) which confirms that energy is simultaneously extracted from six rovibrational lines.

Angular spectrum characteristics of relativistic inverse compton harmonic X-rays

“…The first of these nonlinear effects implies that the radiated spectrum is red-shifted, while the second implies production of n-th harmonic radiation, with the photon energy of 4nγ 2 h L /(1+a L 2 /2). These effects are induced in the electrodynamic sense by the relativistic figure-8 motion [11] (as shown in Figure 1) that results from utilizing a high intensity, and would be relevant for the X-ray modulation such as proposed two color ICS [12] by using potential infrared lasers [13][14]. FIGURE 1.…”

Linear analysis of active-medium two-beam accelerator

“…While the CO 2 has a variety of resonances, the dominant corresponds to 10.6 μm wavelength or ω 0 ¼ 1.78 × 10 14 rad=s; the remaining parameters are inferred based on proven laser systems-BNL [17] and UCLA [18] and other sources, referenced comprehensively in our past publications [10] and [14]. In particular, for pressure of 10 atm, small-signal gain with respect to the intensity at resonance is estimated as α ¼ 1 m −1 , effective bandwidth of the active spectral line as Δω eff ≃ 2π × 37 GHz and dielectric coefficient ε r for the CO 2 ∶N 2 ∶He (1∶1∶14) mixture is taken to be ε r − 1 ≃ 1.42 × 10 −3 .…”

“…Our starting point is to assume the pressure broadening to be a dominant mechanism affecting the spectral linewidth and the Δω to be proportional to the gas mixture pressure. The UCLA group assumes in [18] the CO 2 spectral linewidth to be 37 GHz at 10 atm due to pressure broadening for the CO 2 ∶N 2 ∶He (1∶1∶14) mixture. Explicitly this assumption may be formulated as…”

Generation of high power, sub-picosecond, 10 µm pulses via self-phase modulation followed by compression

“…Finally, there is interest in the generation of keV x-rays by high harmonic generation (HHG) driven by mid-IR pulses since the maximum energy of the x-ray photon scales as λ 2 [4]. Although the picosecond pulses currently available from high power CO 2 laser systems [5,6] are sufficient for laser driven ion acceleration (LDIA), both laser wakefield acceleration and x-ray generation via HHG require sub-picosecond pulses, laser pulses which exceed the ~ 1 THz bandwidth limitation of the CO 2 molecule.…”