Generation of terahertz radiation by relativistic laser pulses on the surface of thick solid targets and thin foils

Terahertz pulse generation from multiterawatt laser surface plasma near thick solid targets and thin foils has been studied. Pulses with energies up to $7 \mu$J were detected in the spectral region $<3$ THz in the direction of specular reflection from the surface of the CaF$_2$ target. The dependence of the terahertz pulse energy ${{W}_{{{\text{THz}}}}}$ on the laser pulse intensity $I_{L}^{\alpha }$ can be approximated by the power function ${{W}_{{{\text{THz}}}}} \sim I_{L}^{\alpha }$ . For a fixed laser pulse duration and variable energy the power index lies in the range $\alpha \approx 1.5$–$2.8$, while for a fixed energy and variable duration $\alpha \approx 1$.