Optimization of multi-cycle two-color laser fields for the generation of an isolated attosecond pulse

Abstract

The effect of the mixing of pulsed two color fields on the generation of an isolated attosecond pulse has been systematically investigated. One main color is 800 nm and the other color (or secondary color) is varied from 1.2 to 2.4 microm. This work shows that the continuum length behaves in a similar way to the behavior of the difference in the square of the amplitude of the strongest and next strongest cycle. As the mixing ratio is increased, the optimal wavelength for the extended continuum shifts toward shorter wavelength side. There is a certain mixing ratio of intensities at which the continuum length bifurcates, i.e., the existence of two optimal wavelengths. As the mixing ratio is further increased, each branch bifurcates again into two sub-branches. This 2D map analysis of the mixing ratio and the wavelength of the secondary field easily allows one to select a proper wavelength and the mixing ratio for a given pulse duration of the primary field. The study shows that an isolated sub-100 attosecond pulse can be generated mixing an 11 fs full-width-half-maximum (FWHM), 800 laser pulse with an 1840 nm FWHM pulse. Furthermore the result reveals that a 33 fs FWHM, 800 nm pulse can produce an isolated pulse below 200 as, when properly mixed.

Advances in laser technology for isolated attosecond pulse generation

“…A similar approach has been proposed by B. Kim et al for the generation of isolated attosecond pulses by a multi-cycle two-color field with a strong component at 800 nm and a weak one in the IR region [49]. Since all these techniques require control of the CEP, several high-energy infrared sources exploiting passive CEP-stabilization have been recently developed for high-order harmonic generation.…”

Generation of an isolated sub-40-as pulse using two-color laser pulses: Combined chirp effects

“…However, the pulse intensity required in RNTS and solid surface harmonic methods is too high (higher than 10 18 W/cm 2 ) to realize in a general laboratory, thus limiting their applications. On the contrary, the method of using HHG from rare gases has been successful and widely used in generating an attosecond pulse because of its requirement of moderate pulse intensity [12][13][14].…”

Control continuum bandwidth and attosecond pulse generation by infrared laser parametric source

“…Polarization gating technique by utilizing the pulse's polarization angle to modulate the HHG process has been realized which relax the laboratory requirement for generating attosecond pulse [13][14][15][16][17][18][19]. Temporal gating is another technique for generating continuum with broader spectral width by superposing two few-cycle pulses [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Recently, Feng et al [19] generate an isolated attosecond pulse by using 20 to 28 fs driving lasers pulse employing polarization gating technology.…”

“…Recently, Feng et al [19] generate an isolated attosecond pulse by using 20 to 28 fs driving lasers pulse employing polarization gating technology. Kim et al created isolated attosecond pulse by adding a weak pulse in the IR region [22]. Liu et al propose a scheme for generating isolated 39-as pulse theoretically by adding a XUV pulse upon the synthesized twocolor field at a proper time [28,29].…”