Strong terahertz radiation from relativistic laser interaction with solid density plasmas

Abstract

We report a plasma-based strong THz source generated in intense laser-solid interactions at relativistic intensities >1018 W/cm2. Energies up to 50 μJ/sr per THz pulse is observed when the laser pulses are incident onto a copper foil at 67.5°. The temporal properties of the THz radiation are measured by a single shot, electro-optic sampling method with a chirped laser pulse. The THz radiation is attributed to the self-organized transient fast electron currents formed along the target surface. Such a source allows potential applications in THz nonlinear physics and provides a diagnostic of transient currents generated in intense laser-solid interactions.

Momentum absorption and magnetic field generation by obliquely incident light

“…Heuristically, the appearance of two different spatial scales is due to the fact that the "forcing" length (ℓ s /2) is different from the "screening" length (c/ω p ). For further simplification we assume ω p ≫ ω, as it is the case for optical laser frequencies and solid-density targets, so that (19) reduces to…”

“…[18] where a first summary of our results was reported. Another possible application of current interest for our analysis is the generation of transient currents on the surface of a laser-irradiated solid target as sources of terahertz pulses [19,20].…”

THz emission control by tuning density profiles of neutral gas targets during intense laser-gas interaction

“…Intense laser interaction with neutral gas targets, especially by two-color femtosecond laser pulses or few-cycle laser pulses, proves to be an efficient way to produce broadband strong THz emission. [5][6][7][8][9][10][11][12][13][14][15][16][17] Among them Yugami et al has found that the radial oscillation of plasma electrons under the electric field of a laser generated immovable ion column can excite radiations around tens and hundreds of GHz in frequency. Besides this, currents can also be generated by ionization process or external fields, which lead to THz emission around the electron plasma frequency.…”

High-energy coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator

“…This produces emission of conical THz radiation with conversion efficiencies as high as 10 −3 , although saturation tends to occur at high laser intensities [18]. Laser-solid interactions at high intensities can produce THz radiation through several mechanisms, which typically involve the excitation of surface currents on solid targets [21][22][23][24][25], embedded plasma dipoles [26] and also coherent transition radiation (CTR) at boundaries and interfaces [27][28][29]. These methods can lead to high energies (in the sub-millijoule range) and high peak electric fields (1-100sMV cm −1 ), which can be scaled with the laser intensity [24,25].…”