Broadband supercontinuum generation method combining mid-infrared chirped-pulse modulation and generalized polarization gating

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

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.

Molecular high-order harmonic spectra and its application to the generation of the isolated attosecond pulse

Molecular high-order harmonic generation (HHG) spectra from H₂⁺ and its application to the generation of the isolated attosecond pulses (IAPs) have been numerically investigated. Results show that (i) the 7th harmonic order is enhanced with the nuclei around the equilibrium internuclear, and as the internuclear distance increased, this enhanced harmonic produces a red-shift (even disappearance). Theoretical analyses show that the electronic transition between the ground and the 1st excited states is responsible for the red-shift enhanced harmonic. (ii) The harmonic spectra exhibit several maxima and minima, and a red-shift of these points is predicted as the internuclear distance increased. (iii) By properly choosing the internuclear distance, the harmonic yield is enhanced, and there is only the single quantum path contributing to the harmonic spectra. (iv) Further, by properly adding the half-cycle pulse as well as the spatial inhomogeneous effect, a 375 eV supercontinuum with a pulse enhancement of 3.9 dB and some attosecond X-ray pulses shorter than 60as can be produced.

Intense supercontinuum generation exceeding 300eV using a two-color field in combination with a 400-nm few-cycle control pulse

We propose a method to control the harmonic process by using a two-color field in combination with a 400-nm few-cycle control pulse for the generation of an ultra-broadband supercontinuum with high efficiency. The ionization and acceleration steps in the harmonic process can be simultaneously controlled by using a three-color field synthesized by a 2000-nm driving pulse and two weak 800-nm and 400-nm control pulses. Then an intense supercontinuum covered by the spectral range from 140 eV to 445 eV is produced. The 3D macroscopic propagation is also employed to select the short quantum path of the supercontinuum, then intense isolated sub-100-as pulses with tunable central wavelengths are directly obtained within water window region. In addition, the generation of isolated attosecond pulses in the far field is also investigated. An isolated 52-as pulse can be generated by using a filter centered on axis to select the harmonics in the far field.