Half-cycle-pulse terahertz emission from an ultrafast laser plasma in a solid target

Abstract

Coherent far-IR radiation is observed upon the generation of dense laser-driven plasma in a solid copper target. The coherent radiation demonstrates a strong half-cycle-pulse nature with temporal dynamics as fast as 150 fs. Comparisons between the data and radiation models are discussed. This measurement demonstrates a new method of performing ultrafast laser-plasma diagnostics in solid targets.

Terahertz radiation by two-color lasers due to the field ionization of gases

“…[6][7][8] indicates that the THz generation discussed here cannot be described simply by the standard nonlinear dielectric polarization in optical media through frequency mixing processes.…”

“…Similar experimental demonstrations with solid plasma can be found in Refs. [3][4][5][6][7]. Such THz radiation shows high energy, broad band and however, large divergence.…”

Strong terahertz radiation form intense femtosecond laser-solid interactions

“…Sagisaka et al report a 0.5 PJ/ sr THz pulse generation from thin foil targets [ 17 ]. The observations show the feasibility to produce strong THz sources with solid targets shined by high intensity laser pulses, though the generation mechanisms are still not well understood [18]. In this letter we will present a >10 PJ/sr strong THz source generated in the intense laser-solid interactions and a new surface electron current model to explain the generation.…”

“…For the laser energy of 130 mJ the THz energy is 5.5 PJ. If taking the pulse duration as ~ picosecond [16,17,18], the peak power of the THz radiation reaches ~50 MW/sr. The energy of the THz radiation monotonously increases with laser energy.…”

Effects of target pre-heating and expansion on terahertz radiation production from intense laser-solid interactions

“…Strong THz emission is induced at both the front [3] and rear surfaces [4] . The sensitivity of THz generation to laser pulse and interaction parameters (such as the pulse energy, polarization, and incident angle) were reported in both 100-femtosecond-level (or even shorter) duration regimes and in the weakly relativistic or nonrelativistic intensity regimes [3,[10][11][12][13] . The influence of the preplasma generated at the front surface of the target foil has also been explored [10] .…”