Generation of isolated attosecond pulses in CdS semiconductor using polarization gating technique and tailored two-color pulse system

Abstract

This research uses a two-color pulse system and polarization gating technique to generate single attosecond pulses from femtosecond laser interaction with cadmium sulfide semiconductor. The rotating elliptical polarization two-color pulse system is designed to produce attosecond pulses up to 420 as. Also, the intensity of the single attosecond pulse can be improved by using a two-color-polarizing gate technique. In this presented modifications, the isolated attosecond pulse with greater intensity and a shorter time width of about 400 as is generated. Generation of such an intense isolated attosecond pulse is a great achievement that helps for measuring the ultrafast phenomena.

Keywords: Attosecond pulse; High harmonic generation; Polarization gating method; Two-color pulse system..

Fig. 1

(a) The electric field profile for linearly polarized laser pulse with the characteristics: Gaussian envelope, λ = 3 μm, the intensity I = 1 TWcm⁻², FWHM of 30 fs, and initial phase ϕ₀ = 0. (b) High harmonic spectra for inter-band current (, black line) and intra-band current ((, red line) and T₂ = 1.3 fs. (c) Corresponding attosecond pulse from the superposition of harmonics from 9th to 26th and T₂ = 1.3 fs. (d) Time-frequency profile by using the Gabor transform for T₂ = 1.3 fs.

Fig. 2

(a) The electric field profile of a two-color pulse system with the characteristics: the laser intensities of I₁ = 1 TW cm⁻² and I₂ = 0.1 TW cm⁻² , λ₁ = 3 μm and λ₂ = 1.5 μm, FWHM of 30 fs and. (b) Total high harmonic spectrum for T₂ = 1.3 fs. (c) Corresponding single attosecond pulse from the superposition of harmonics from 8^h to 22th and T₂ = 1.3 fs. (d) Time-frequency profile by using the Gabor transform for T₂ = 1.3 f s.

Fig. 3

(a) Ellipticity dependence of the intensity and the time width of the resulting attosecond pulses from the interaction of CdS with an elliptically polarized two-color pulse system on the ellipticity of the driving laser field with the characteristics: the laser intensities of I₁ = 1TW cm⁻² and I₂ = 0.1 TW cm⁻² λ₁ = 3 μm and λ₂ = 1.5 μm, FWHM of 30 fs, and. (b) Total high harmonic spectrum for T₂ = 1.3 fs, ϵ = 0.5. (c) Corresponding single attosecond pulse from the superposition of harmonics from 8^h to 24th and T₂ = 1.3 fs and ϵ = 0.5. (d) Time-frequency profile by using the Gabor transform for T₂ = 1.3 fs and ϵ = 0.5.

Fig. 4

(a) Dependence of the intensity and time width of the resulting attosecond pulses from the interaction of CdS with an elliptically polarized two-color pulse system and ϵ = 0.5 on the orientation angle of the laser polarization with the following characteristics: the laser intensities of I₁ = 1 TW cm⁻² and I₂ = 0.1 TW cm⁻², λ₁ = 3 μm, and λ₂ = 1.5 μm, FWHM of 30 fs, ϵ = 0.5 , and polarization rotation of 10^o. (b) Total high harmonic spectrum for T₂ = 1.3 fs and polarization rotation of 10^o. (c) Corresponding single attosecond pulse from the superposition of harmonics from 6th to 24th and T₂ = 1.3 fs with polarization rotation of 10°. (d) Time-frequency profile by using the Gabor transform for T₂ = 1.3 fs and polarization rotation of 10°.

Fig. 5

(a) The electric field of a polarization gating pulse system with the intensities of I₁ = I₂ = 10¹² Wcm⁻², wavelengths of, δ = 1.5T₁ , and φ_cep = π/2. (b) Total high harmonic spectrum. (c) Corresponding single attosecond pulse from the superposition of harmonics from 8th to 26th. (d) Time-frequency profile by using the Gabor transform.

Fig. 6

The intensity and time width of the obtained attosecond pulses for each γ resulted from interaction of CdS target with a laser pulse, δ = 1.5T₁,and φ_cep = π/2.

Fig. 7

The intensity and time width of the obtained attosecond pulses for different ellipticity parameters resulted from interaction of CdS target with a laser pulse, δ = 1.5T₁,and φ_cep = π/2.

Fig. 8

(a) The electric field of an elliptically polarized two-color gating pulse system with the intensities of I₁ = 1 TW cm⁻² and I₂ = 0.8 TW cm⁻², wavelengths of , δ = 1.5T₁,and φ_cep = π/2. (b) Total high harmonic spectrum. (c) Corresponding single attosecond pulse from the superposition of harmonics from 8th to 26th. (d) Time-frequency profile by using the Gabor transform.