Paper
7 September 2011 Tunable terahertz radiation from an ultrashort-laser-pulse-induced discharge in biased air
Fuminori Suzuki, Hiroaki Anno-Kashiwazaki, Jun Miyazawa, Shohei Ono, Takeshi Higashiguchi, Noboru Yugami, Yasuhiko Sentoku, Ryosuke Kodama, Patric Muggli
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Abstract
Strong beams of coherent radiation are essential to induce nonlinear excitation phenomena in biology and material sciences. Optical-field-induced ionization by an ultrashort laser pulse produces ultrabroadband bursts of radiation with photon energies ranging from radio-wave at the microsecond timescale to x-ray at the attosecond timescale. As the laser pulse drives an ultrafast-discharge with high current it induces nonlinear spectral conversion in a few femtoseconds and generates terahertz electromagnetic waves. Broadband terahertz generation has been reported in air and rare gases. If the radiation frequency depends on the electron plasma density, it should vary with the laser pulse intensity, and the kind and density of the gas. However, the peak radiation frequencies reported are almost independent of those parameters. From the laser-gas interaction point of view, the terahertz generation mechanism is not enough understood. We demonstrate a frequency-tuning scheme that uses the laser pulse duration to control the ultrafast-discharge current timescale, yielding a terahertz energy of 0.1 μJ and a conversion efficiency of 10-4 by use of the homemade power supply with 60-A discharge current at 1 kHz. We also propose a simple physical model to explain the generation of terahertz radiation with the laser propagation in an ultrafast-discharge.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fuminori Suzuki, Hiroaki Anno-Kashiwazaki, Jun Miyazawa, Shohei Ono, Takeshi Higashiguchi, Noboru Yugami, Yasuhiko Sentoku, Ryosuke Kodama, and Patric Muggli "Tunable terahertz radiation from an ultrashort-laser-pulse-induced discharge in biased air", Proc. SPIE 8119, Terahertz Emitters, Receivers, and Applications II, 81190M (7 September 2011); https://doi.org/10.1117/12.892902
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KEYWORDS
Terahertz radiation

Plasma

Pulsed laser operation

Ionization

Laser energy

Ultrafast phenomena

Electrodes

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