Terahertz wave generation in nitrogen gas using shaped optical pulses

Yamaguchi, Masashi; Das, Jayashis

doi:10.1364/josab.26.000a90

Cited by 16 publications

(7 citation statements)

References 23 publications

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“…Table 1 lists the relaxation time τ 1 and τ 2 for different powers of preplasma. The fitted value of τ 2 matches closely with the reported value of (1.1 0.6 ps, [13]) electron and N 4 ion recombination time. A more detailed calculation is needed to confirm that this reduction in THz power is related to this fast recombination rate of electrons and N 4 ions.…”

Section: Discussionsupporting

confidence: 86%

“…The entire setup was purged with dry nitrogen gas in both cases. For the measurements of THz wave spectrum, THz Michelson interferometer setup described in [13] was used for the detection. The interferometer is advantageous over the conventional electro-optic sampling scheme due to the broader bandwidth, and it is particularly useful for the detection of THz wave generated from air.…”

Section: Methodsmentioning

confidence: 99%

“…Since ionization of gas molecules is involved in the generation process [11], the generation process is highly sensitive to the temporal shape of the optical pulses when the electric field is close to the ionization threshold. THz pulse shaping and optimization in gas plasma has been demonstrated using phase-shaped optical pulses and genetic algorithms [12,13].…”

Section: Introductionmentioning

confidence: 99%

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Terahertz wave excitation from preexisting air plasma

Das

Yamaguchi

2013

J. Opt. Soc. Am. B

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Terahertz (THz) wave generation process in air plasma was studied using femtosecond laser pulse pairs. The effect of preexisting air plasma was investigated using two optical geometries: collinear and orthogonal pumping geometry. When the air plasma is excited in collinear geometry, the power of the generated THz wave shows asymmetric dependence on the relative delay of these pulses. The asymmetry depends on the relative intensities of these pump pulses, and it disappears when the pulses have equal intensities. In the orthogonal pumping geometry, the power of the THZ wave generated by the main pump pulse decreases in the presence of the preexisting plasma generated by the prepulse, and it recovers as the relative delay between the prepulse and main pulses becomes longer. Possible mechanisms of the results are discussed in terms of the dynamics of free electrons in the air plasma.

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Section: Discussionsupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Terahertz wave excitation from preexisting air plasma

Das

Yamaguchi

2013

J. Opt. Soc. Am. B

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“…The second harmonic pulses were generated by using a type I beta barium borate (BBO) crystal, and both of the fundamental and second harmonic pulses were focused into nitrogen gas to generate THz waves. THz Michelson interferometer48 were used to characterize the THz pulse width and spectrum. The THz pump and optical probe pulses were combined using an ITO glass plate and focused with an off-axis parabolic mirror.…”

Section: Methodsmentioning

confidence: 99%

Coherent Excitation of Optical Phonons in GaAs by Broadband Terahertz Pulses

Yamaguchi

2016

Sci Rep

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Coherent excitation and control of lattice motion by electromagnetic radiation in optical frequency range has been reported through variety of indirect interaction mechanisms with phonon modes. However, coherent phonon excitation by direct interaction of electromagnetic radiation and nuclei has not been demonstrated experimentally in terahertz (THz) frequency range mainly due to the lack of THz emitters with broad bandwidth suitable for the purpose. We report the experimental observation of coherent phonon excitation and detection in GaAs using ultrafast THz-pump/optical-probe scheme. From the results of THz pump field dependence, pump/probe polarization dependence, and crystal orientation dependence, we attributed THz wave absorption and linear electro-optic effect to the excitation and detection mechanisms of coherent polar TO phonons. Furthermore, the carrier density dependence of the interaction of coherent phonons and free carriers is reported.

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“…The generation and detection techniques of broadband THz radiation have been widely studied and investigated in the last few decades [3]. The flexibility of application of terahertz radiation can be expanded by manipulating the terahertz radiation in different aspects such as the output power tuning [4][5][6][7][8][9], spectrum tuning [10][11][12][13][14][15], polarization tuning [16][17][18] and so on. Among these, the frequency tuning technique is still highly desirable and challenging.…”

Section: Introductionmentioning

confidence: 99%

Frequency blue shift of terahertz radiation from femtosecond laser induced air plasmas

et al. 2021

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The peak frequency of the terahertz radiation generated from the femtosecond laser induced air plasmas is blue shifted with the increased second harmonics intensity when a high voltage is added upon the air plasmas. This blue shift is the result of the DC-biased field from the high voltage plus the AC-biased field from the second harmonics, indicating that this terahertz radiation frequency peak is tunable by varying the two field components. This tunable frequency peak is significant to various applications such as remote sensing and material characterization.

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Terahertz wave generation in nitrogen gas using shaped optical pulses

Cited by 16 publications

References 23 publications

Terahertz wave excitation from preexisting air plasma

Terahertz wave excitation from preexisting air plasma

Coherent Excitation of Optical Phonons in GaAs by Broadband Terahertz Pulses

Frequency blue shift of terahertz radiation from femtosecond laser induced air plasmas

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