Fraunhofer type diffraction of phase-modulated broad-band femtosecond pulses

Dakova, A.; Kovachev, L. M.; Kovachev, Kamen L.; Dakova, D.

doi:10.1088/1742-6596/594/1/012023

Cited by 3 publications

(10 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another standard restriction in the filamentation theory is the use of one-component scalar approximation of the electrical field E. This approximation, though, is in contradiction with recent experimental results, where rotation of the polarization vector is observed [8]. For this reason in the present paper we use non-paraxial vector model in circular basis (24), in which the nonlinear effects are described by the nonlinear polarization components (5). The dispersion number in air is very small: β = k 0 v 2 gr k ′′ ≃ 2.1 × 10 −5 , so we can solve Eqs.…”

Section: Nonlinear Polarizationmentioning

confidence: 84%

“…Our soliton solution is obtained for pulses which satisfy the additional condition ∆k z ≈ k 0 . The diffraction of broad-band pulses is not the Fresnel one [23,24], which leads to the conclusion that the soliton appears as a balance between semi-spherical (Fraunhofer type) diffraction and nonlinear self-focusing. The solution gives also a rotation of the vector of the electrical field with the carrier to envelope frequency.…”

Section: Discussionmentioning

confidence: 99%

“…It is important to mentoin that from Eqs. (24) paraxial spatio-temporal approximation can be derived for narrow-band laser pulses [22] only. The filamentation experiments demonstrate quite different pulse evolution: the initial laser pulse (t 0 ≥ 50f s) possesses a relatively narrow-band spectrum (∆k z ≪ k 0 ) and during the process the initial self-focusing and self-compression the spectrum broadens significantly.…”

Section: Nonlinear Polarizationmentioning

confidence: 99%

“…That why we do not reduce more Eqs. (24) and try to solve them for the case when the pulse has a large spectrum.…”

Section: Nonlinear Polarizationmentioning

confidence: 99%

“…The dispersion number in air is very small: β = k 0 v 2 gr k ′′ ≃ 2.1 × 10 −5 , so we can solve Eqs. (24) in approximation up to the first order of dispersion. Additionally, we will use the normalized amplitude functions A ± = A 0 A ± to rewrite the system (22) in the form…”

Section: Nonlinear Polarizationmentioning

confidence: 99%

See 4 more Smart Citations

The light filament as a new nonlinear polarization state

Kovachev

2015

Preprint

View full text Add to dashboard Cite

We present an analytical approach to the theory of nonlinear propagation in gases of femtosecond optical pulses with broad-band spectrum . The vector character of the nonlinear third-order polarization of the electrical field in air is investigated in details. A new polarization state is presented by using left-hand and right-hand circular components of the electrical field . The corresponding system of vector amplitude equations is derived in the rotating basis. We found that this system of nonlinear equations has 3D + 1 vector soliton solutions with Lorentz shape. The solution presents a relatively stable propagation and rotation with GHz frequency of the vector of the electrical field in a plane orthogonal to the direction of propagation. The evolution of the intensity profile demonstrates a weak self-compression and a week spherical wave in the first milliseconds of propagation.

show abstract

Section: Nonlinear Polarizationmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Nonlinear Polarizationmentioning

confidence: 99%

“…That why we do not reduce more Eqs. (24) and try to solve them for the case when the pulse has a large spectrum.…”

Section: Nonlinear Polarizationmentioning

confidence: 99%

Section: Nonlinear Polarizationmentioning

confidence: 99%

See 3 more Smart Citations

The light filament as a new nonlinear polarization state

Kovachev

2015

Preprint

View full text Add to dashboard Cite

show abstract

Linear and Nonlinear Optics of Broad-Band Laser Pulses: Diffraction

Iordanova,

Miteva,

Dakova

et al. 2024

ACS Omega

View full text Add to dashboard Cite

The typical spectrally limited laser pulse in the nearinfrared region is narrow-band up to 40−50 fs. Its spectral width Δk is much smaller than the carrying wavenumber k 0 (Δk ≪ k 0 ) . For such kinds of pulses, on distances of a few diffraction lengths, the diffraction is of a Fresnel's type and their evolution can be described correctly in the frame of the well-known paraxial evolution equation. The technology established in 1985 of amplification through chirping of laser pulses triggered remarkable progress in laser optics along with the construction of femtosecond (fs) laser facilities producing high intensity fields of the order of 10 15 −10 21 W/cm 2 . However, the duration of the pulse was quickly shortened from picoseconds down to 5−6 fs, which have a broadband nature (Δk ∼ k 0 ). The linear and nonlinear propagation dynamics of broad-band pulses is quite different form their narrowband counterparts. Here, we review the appropriate theoretical approach to study the evolution of the pulse. Moreover, we shed light on the different diffraction regimes inherent to both narrow-band and broad-band laser pulses and compare them to unveil the main differences. Using this very method, in subsequent papers, we will investigate the influence of the dispersion and nonlinearity on the laser pulse propagation in isotropic media.

show abstract