Generation of terahertz radiation by the optical breakdown induced by a bichromatic laser pulse

Ахмеджанов, Р. А.; Ilyakov, Igor; Миронов, В. А.; Суворов, Е. В.; Фадеев, Д. А.; Shishkin, B. V.

doi:10.1134/s1063776109090027

Cited by 19 publications

(13 citation statements)

References 17 publications

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“…The peak plasma density was set to 10 18 cm -3 , diameter of the spark equals to 80 mkm, the length of the spark was about 2 mm. The obtained terahertz waveform, spectrum and radiation pattern are in good agreement with experimental data [5,10].…”

Section: Iitheorysupporting

confidence: 85%

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Specific features of terahertz radiation from air plasma generated by both the first and the second optical harmonics

Миронов

Фадеев

2010

35th International Conference on Infrared, Millimeter, and Terahertz Waves

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Section: Iitheorysupporting

confidence: 85%

“…Comparatively recently a new approach for calculation of low frequency current in plasma generated by a bichromatic pulse based on an explicit averaging of velocities of free electrons appearing during breakdown of air according to Keldysh ionization law in tunneling limit was proposed [6]. In the work we develop this trend basing on rather new approach [10].…”

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confidence: 99%

Specific features of terahertz radiation from air plasma generated by both the first and the second optical harmonics

Миронов

Фадеев

2010

35th International Conference on Infrared, Millimeter, and Terahertz Waves

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“…Both fundamental and second harmonic radiation were focused sharply in the atmospheric air. Terahertz wave radiation was generated under the "two-colored" optical pumping via the nonlinearity of the air discharge plasma [13], [14]. The emerging terahertz beam was collimated with an off-axis parabolic mirror, sent to the test specimen and then focused with another parabolic mirror onto the nonlinear crystal (GaP, 200 m length) of the detection system.…”

Section: Experimental Setup and Samplesmentioning

confidence: 99%

Scattering Effects in Terahertz Wave Spectroscopy of Granulated Solids

Kornienko

Ахмеджанов

Ilyakov

et al. 2015

IEEE Trans. THz Sci. Technol.

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Applications of terahertz spectroscopy methods to granulated solids are substantially constrained by the effects of scattering of the incident terahertz waves by spatial heterogeneities of a sample. The experimental results obtained by means of terahertz time-domain spectroscopy are reported for the samples of granulated 2, 4-dinitrotoluene and alpha-lactose without any special filling. We show that in samples of the same substance, but prepared in a different manner, the overall increase of the background extinction with frequency and appearance of additional extinction maxima can obscure the true absorption features of the material. In samples with large grain size, of order of 400 m, a complicated irregular spectral structure is observed instead of a fingerprint maxima at 1.37 THz for alpha-lactose and at 1.08 THz for 2,4-dinitrotoluene. At higher frequencies no true spectral fingerprints are clearly seen in the raw experimental spectra of all the samples with the grain sizes of 130 m and more. The influence of grain size, air-filling factor and the dispersion properties of the materials is studied. Theoretical analysis is made with the use of Mie theory in simplifying approximations and taking into account interference between the waves transmitted through a porous sample. It has been shown that the scattering-induced masking effects can be properly simulated even for the air-filled objects with initially unknown spatial and dispersion parameters. The procedure of eliminating the influence of scattering effects from the raw spectral data is proposed. Detection of true high-frequency spectral fingerprints is demonstrated using this procedure for various grain sizes up to 400 m.Index Terms-Electromagnetic interference, electromagnetic propagation in absorbing media, submillimeter-wave measurements, submillimeter-wave propagation.

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“…The dependences of the parameters of terahertz radiation on the characteristics of focusing lenses were analyzed [11]. The possibility of controlling the orien tation of the polarization of terahertz radiation was demonstrated [12][13][14].One of the first detailed theoretical and experimen tal investigations of the generation of terahertz radia tion in a plasma produced by focused two frequency optical pulses was performed in [15]. A model of the generation of terahertz radiation based on the consid eration of the excitation of a macroscopic residual electron current was proposed in [15,16].…”

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confidence: 99%

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confidence: 99%

Generation of terahertz radiation at optical breakdown of air: The dependence of the optimal phase shift between the components of a two-color laser pulse on their intensity

et al. 2015

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74Terahertz radiation (10 11 -10 13 Hz) is of interest because of its possible application for identification of substances, biomedical diagnostics, tomography, security [1,2], and other problems. Optical methods are now actively used for the generation of terahertz radiation with the use of femtosecond laser pulses. Terahertz radiation generated in such schemes is a subpicosecond pulse with the time dependence of the electric field strength that contains only one or two oscillations and has a very broad spectrum. At the appropriate duration of laser pulses and the method of generation, the useful spectrum of terahertz radiation can cover the frequency range of 100 GHz to 100 THz [3].Converters based on a gas ionized by focused fem tosecond laser pulses are of great interest for optical methods of generation of terahertz radiation. This interest is due both to the absence of phonon absorp tion lines in a plasma, which makes it possible to obtain terahertz radiation with a continuous spectrum in the entire terahertz range, and to the possibility of creation of a remote source and a remote detector of terahertz radiation in the atmosphere, which allows remote studies of various objects in the atmosphere [4]. As was demonstrated experimentally, pulses of ter ahertz radiation can be obtained at focusing of femto second optical pulses in gases by spherical [5, 6] and axicon [7] lenses. The best results were obtained when using spherical lenses and two color optical pulses composed of the first (ω) and second (2ω) harmonics [8]. The two color generation scheme has been actively studied since 2000, when a high efficiency of this generation scheme, as well as the existence of an optimal phase shift between radiation at frequencies ω and 2ω, was demonstrated [9]. It was shown that the maximum efficiency of conversion is achieved with linearly polarized components of a laser pulse at fre quencies ω and 2ω with coinciding polarization planes [10]. The dependences of the parameters of terahertz radiation on the characteristics of focusing lenses were analyzed [11]. The possibility of controlling the orien tation of the polarization of terahertz radiation was demonstrated [12][13][14].One of the first detailed theoretical and experimen tal investigations of the generation of terahertz radia tion in a plasma produced by focused two frequency optical pulses was performed in [15]. A model of the generation of terahertz radiation based on the consid eration of the excitation of a macroscopic residual electron current was proposed in [15,16]. A semiclas sical model was used to calculate a nonlinear current, whose excitation efficiency significantly determines the efficiency of the generation of terahertz radiation. The electron density in this model was determined within the Ammosov-Delone-Krainov theory [17,18], which describes ionization in the tunneling limit, and their trajectories were calculated in the strong field approximation. A clear model proposed in [15,16] provided an explanation of a number of dependences of the char...

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Generation of terahertz radiation by the optical breakdown induced by a bichromatic laser pulse

Cited by 19 publications

References 17 publications

Specific features of terahertz radiation from air plasma generated by both the first and the second optical harmonics

Specific features of terahertz radiation from air plasma generated by both the first and the second optical harmonics

Scattering Effects in Terahertz Wave Spectroscopy of Granulated Solids

Generation of terahertz radiation at optical breakdown of air: The dependence of the optimal phase shift between the components of a two-color laser pulse on their intensity

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