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

Tokita S, Sakabe S, Nagashima T, Hashida M, Inoue S - Sci Rep (2015)

Bottom Line: Here, ultrafast field propagation along a metal wire driven by a femtosecond laser pulse with an intensity of 10(18) W/cm(2) 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.

View Article: PubMed Central - PubMed

Affiliation: 1] Advanced Research Center for Beam Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan [2] Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501, Japan.

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 10(18) W/cm(2) 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.

No MeSH data available.


Related in: MedlinePlus

Time traces of electron beam deflections in the x and y directions for the waveform measurement of a reflected surface wave at d = 15 mm.The distance from the end of the wire to the position where the probe beam crosses the wire is 13 ± 0.5 mm.
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f4: Time traces of electron beam deflections in the x and y directions for the waveform measurement of a reflected surface wave at d = 15 mm.The distance from the end of the wire to the position where the probe beam crosses the wire is 13 ± 0.5 mm.

Mentions: Second, to observe the reflected pulse by using the electron probe within the adjustable delay range, the distance between the end of the wire and the position where the probe beam crosses the wire was shortened from 28 mm to 13 mm. The results are shown in Fig. 4. A peak at 51 ps and another at 137 ps are observed in the time trace of the y deflection. The delay of Δt = 86 ps between the two peaks agrees with the round-trip time of a pulse propagating at the speed of light over the distance between the detection point and the end of the wire (c·Δt ≈ 2 × 13 mm). As described below, the y and x deflections correspond to the electric and magnetic field strengths, respectively, when assuming a fundamental TM surface wave. Thus, it is consistent that the time traces of the x deflections around 51 and 137 ps have opposite slopes, because the electromagnetic wave should have opposite magnetic fields before and after reflection as a consequence of traveling in opposite directions. Taken together, these results strongly suggest that a strong surface wave propagates along the metal wire.


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

Tokita S, Sakabe S, Nagashima T, Hashida M, Inoue S - Sci Rep (2015)

Time traces of electron beam deflections in the x and y directions for the waveform measurement of a reflected surface wave at d = 15 mm.The distance from the end of the wire to the position where the probe beam crosses the wire is 13 ± 0.5 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4317702&req=5

f4: Time traces of electron beam deflections in the x and y directions for the waveform measurement of a reflected surface wave at d = 15 mm.The distance from the end of the wire to the position where the probe beam crosses the wire is 13 ± 0.5 mm.
Mentions: Second, to observe the reflected pulse by using the electron probe within the adjustable delay range, the distance between the end of the wire and the position where the probe beam crosses the wire was shortened from 28 mm to 13 mm. The results are shown in Fig. 4. A peak at 51 ps and another at 137 ps are observed in the time trace of the y deflection. The delay of Δt = 86 ps between the two peaks agrees with the round-trip time of a pulse propagating at the speed of light over the distance between the detection point and the end of the wire (c·Δt ≈ 2 × 13 mm). As described below, the y and x deflections correspond to the electric and magnetic field strengths, respectively, when assuming a fundamental TM surface wave. Thus, it is consistent that the time traces of the x deflections around 51 and 137 ps have opposite slopes, because the electromagnetic wave should have opposite magnetic fields before and after reflection as a consequence of traveling in opposite directions. Taken together, these results strongly suggest that a strong surface wave propagates along the metal wire.

Bottom Line: Here, ultrafast field propagation along a metal wire driven by a femtosecond laser pulse with an intensity of 10(18) W/cm(2) 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.

View Article: PubMed Central - PubMed

Affiliation: 1] Advanced Research Center for Beam Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan [2] Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501, Japan.

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 10(18) W/cm(2) 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.

No MeSH data available.


Related in: MedlinePlus