Strong sub-terahertz surface waves generated on a metal wire by high-intensity laser pulses

Abstract

Terahertz pulses trapped as surface waves on a wire waveguide can be flexibly transmitted and focused to sub-wavelength dimensions by using, for example, a tapered tip. This is particularly useful for applications that require high-field pulses. However, the generation of strong terahertz surface waves on a wire waveguide remains a challenge. Here, ultrafast field propagation along a metal wire driven by a femtosecond laser pulse with an intensity of 1018 W/cm2 is characterized by femtosecond electron deflectometry. From experimental and numerical results, we conclude that the field propagating at the speed of light is a half-cycle transverse-magnetic surface wave excited on the wire and a considerable portion of the kinetic energy of laser-produced fast electrons can be transferred to the sub-surface wave. The peak electric field strength of the surface wave and the pulse duration are estimated to be 200 MV/m and 7 ps, respectively.

Induction of subterahertz surface waves on a metal wire by intense laser interaction with a foil

“…The electric field has almost the same sub-picosecond rise time for each distance. The polarity of the electric field of the surface wave is opposite to that obtained by irradiating the wire by the laser directly[18]. That is, the electric field is directed toward the wire center.…”

“…In particular, linearly polarized THz waves propagating through free space cannot be transferred to the waveguide efficiently. However, it was demonstrated recently that a sub-THz surface wave could be generated by the interaction between an intense laser pulse (intensity: 10 18 W/cm 2 ) and a metal wire [18]. The field strength of the surface wave was 200 MV/m and the pulse duration was 7 ps.…”

Proton array focused by a laser-irradiated mesh

“…2(b2) as observed in [32] and in [39], extending to the whole mesh within 3.5 ps. The propagation of an ultrashort EM pulse is associated to this process as observed in several experiments and simulations [21,33,34]. with higher amplitude, such as 10 9 V/m, proton beams will be focused too soon after the mesh and then diverge so that no focusing effect can be obtained at detection plane.…”

“…As a result, the beam is divided into several beamlets and a shadow of the mesh structure is recorded on the RCF [30]. Furthermore, strong, transient fields will be generated on the mesh [31][32][33], owing to the irradiation of CPA2 and the expulsion of relativistic electrons from the mesh wires [34]. If the protons (generated from the rear surface of the Al foil) reach the mesh target while these fields are present, they are also acted upon by the fields, in addition to the collisional effects.…”

Laser induced THz Sommerfeld waves along metal wire

“…The thin metal wires can be utilized for guiding electron bunches [1,2] as well as surface waves [3] during generation from irradiation of a wire target by short relativistically intense laser pulse. In such interaction a strong impulse type Thz surface wave can be excited at the metal surface due to a current of the high energy escaping electrons and electric sheath formation.…”