Investigating the influence of incident laser wavelength and polarization on particle acceleration and terahertz generation

The interaction of a high-power laser pulse with a thin foil can generate energetic, broadband terahertz radiation. Here, we report an experimental investigation on the influence of incident laser polarization and wavelength on the terahertz emission and maximum proton energy from the target rear surface. For similar incident laser intensities, the characteristics of the particle beams and the terahertz radiation show a wavelength dependence. The results fit well with the established scaling laws for the terahertz yield and the maximum proton energy as a function of the incident laser irradiance ($I{\lambda }^2$).

Figure 1

Experimental schematic and the diagnostics. Inset: Temporal contrast of the $\omega$ and $2\omega$ laser pulses.

Figure 2

(a) Temporal profile of the THz pulses generated for various incident polarization conditions and (b) the corresponding proton spectra.

Figure 3

(a) Temporal profile of the THz pulses generated with $\omega$ and $2\omega$ and (b) the corresponding proton spectra.

Figure 4

(a) Scaling of THz yield. (b) Maximum proton energy with incident laser irradiance $I{\lambda }^2$.