Enhancement of attosecond pulse in water window region by using pump-probe approach

2018 ◽  
Vol 32 (29) ◽  
pp. 1850318 ◽  
Author(s):  
Hang Liu ◽  
Yi Li ◽  
Rich S. Castle
Keyword(s):  
Probe Pulse ◽  
Fourier Transformation ◽  
Pulse Signal ◽  
Ionization Probability ◽  
Probe Laser ◽  
Resonance Ionization ◽  
Pump Probe ◽  
Mid Infrared ◽  
Water Window ◽  
Window Region

An effective scheme to enhance the harmonic yield and the attosecond (as) pulse signal from H[Formula: see text] has been proposed by using the pump-probe laser field. It is found that with the help of the multi-cycle pump pulse, H[Formula: see text] can be steered into the resonance ionization regions, where the ionization probability can be remarkably enhanced. Thus, the harmonic yield can be remarkably enhanced when a sequential mid-infrared probe pulse is added. Further, by modulating the phase of the probe pulse and by adding a controlling pulse, the harmonic cutoff can be extended up to the water window region. Finally, by the Fourier transformation of the selected harmonics on the harmonic supercontinuum, the water window attosecond pulses as short as 25 as can be obtained.

Generation of a coherent x ray in the water window region at 1 kHz repetition rate using a mid-infrared pump source

2009 ◽  
Vol 34 (11) ◽  
pp. 1747 ◽  
Author(s):  
Hui Xiong ◽  
Han Xu ◽  
Yuxi Fu ◽  
Jinping Yao ◽  
Bin Zeng ◽  
...  
Keyword(s):  
Repetition Rate ◽  
Mid Infrared ◽  
X Ray ◽  
Water Window ◽  
Pump Source ◽  
Window Region

scholarly journals Towards GW-Scale Isolated Attosecond Pulse Far beyond Carbon K-Edge Driven by Mid-Infrared Waveform Synthesizer

2018 ◽  
Vol 8 (12) ◽  
pp. 2451 ◽  
Author(s):  
Yuxi Fu ◽  
Hua Yuan ◽  
Katsumi Midorikawa ◽  
Pengfei Lan ◽  
Eiji Takahashi
Keyword(s):  
Single Cycle ◽  
High Order Harmonic Generation ◽  
Mid Infrared ◽  
X Ray ◽  
Water Window ◽  
High Order Harmonic ◽  
Optical Parametric ◽  
Isolated Attosecond Pulse ◽  
Window Region ◽  
The Continuum

We discuss the efficient generation of intense “water window” (0.28–0.54 keV) isolated attosecond pulses (IAPs) using a mid-infrared (MIR) waveform synthesizer. Our numerical simulations clearly indicate that not only a longer-wavelength driving laser but also a weak control pulse in the waveform synthesizer helps extend the continuum cutoff region and reduce the temporal chirp of IAPs in high-order harmonic generation (HHG). This insight indicates that a single-cycle laser field is not an optimum waveform for generating the shortest IAP from the veiwpoints of reducing the attochirp and increasing the efficiency of HHG. By combining a waveform synthesizer technology and a 100 mJ MIR femtosecond pulse based on a dual-chirped optical parametric amplification (DC-OPA) method, a gigawatt-scale IAP (55 as with 10 nJ order) in the water window region can be generated even without attochirp compensation. The MIR waveform synthesizer is highly beneficial for generating a shorter IAP duration in the soft X-ray region because there are no suitable transparent dispersive materials that can be used for compressing the attochirp.

Selection and Enhancement of the Single Harmonic Emission Event in the Water Window Region

2018 ◽  
Vol 73 (11) ◽  
pp. 985-994 ◽  
Author(s):  
Hang Liu ◽  
A. Yuanzi Feng
Keyword(s):  
Fourier Transformation ◽  
Half Cycle ◽  
Laser Polarization ◽  
High Order Harmonic Generation ◽  
Harmonic Emission ◽  
Water Window ◽  
Polarization Gating ◽  
High Order Harmonic ◽  
Window Region ◽  
Cycle Pulse

AbstractThe control of the high-order harmonic generation in the half-cycle region has been investigated by using the improved polarization gating (PG) technology. It is found that by properly controlling the delay time of the PG pulse, the contribution of the harmonic plateau is nearly coming from the single harmonic emission event, which is much better for producing the single attosecond pulses (SAPs). Further, by properly adding an ultraviolet pulse and a half-cycle pulse in the driven laser polarization direction, the harmonic yield can be enhanced and the harmonic cutoff can be extended, showing a high-intensity harmonic plateau covering the whole water window region. Finally, through the Fourier transformation of some selected harmonics, a 35 as SAP in the water window region can be obtained.

Generation of water window single attosecond pulse from multi-cycle mid-infrared laser field with chirp gating modulation

2019 ◽  
Vol 33 (06) ◽  
pp. 1950064 ◽  
Author(s):  
Hang Liu ◽  
Henry M. Schafer ◽  
R. L. Q. Feng ◽  
A. Yuanzi Feng
Keyword(s):  
Pulse Duration ◽  
Laser Field ◽  
Initial State ◽  
Mid Infrared ◽  
Water Window ◽  
High Order Harmonic ◽  
Chirp Modulation ◽  
Window Region ◽  
Gating Modulation ◽  
Cycle Pulse

A potential scheme to produce the water window single attosecond pulses (SAPs) from the multi-cycle mid-infrared (MIR) laser field has been investigated with the help of the chirp gating modulation. It is found that with the introduction of the laser chirp (i.e. up-chirp or down-chirp modulation), the extension of the harmonic cutoff can be achieved and the single harmonic radiation peak (HRP) can be selected during the harmonic emission process. Moreover, the chirp gating modulation on the high-order harmonic generation (HHG) is sensitive to the few-cycle pulse duration, but it is not very sensitive to the multi-cycle pulse duration. Moreover, a larger extension of the harmonic cutoff covering the whole water window region can be found with the help of the multi-cycle down-chirp modulation. Further, by properly choosing the coherent superposition of the ground state and the high Rydberg state as the initial state, the efficiency of HHG can be enhanced by 5 orders of magnitude. Finally, a series of high-intensity sub-40as pulses covering the water window region can be obtained.

Pump-Probe Laser Photolytic Fragmentation Fluorescence Spectrometry of Isomeric Alkenes

1994 ◽  
Vol 48 (5) ◽  
pp. 616-619 ◽  
Author(s):  
Bobby J. Stanton ◽  
E. T. Monroe ◽  
E. L. Wehry
Keyword(s):  
Fluorescence Intensity ◽  
Laser Fluence ◽  
Laser Wavelength ◽  
Fluorescence Spectrometry ◽  
Probe Laser ◽  
Intermediate Species ◽  
Pump Probe ◽  
Laser Pump ◽  
Photolysis Laser ◽  
Spectral Patterns

The two-laser “pump-probe” photolytic fragmentation fluorescence spectrometry of three octenes and two nonenes is described. Probe-laser-induced C2 fluorescence (Deslandres-d'Azambuja system, C1II g→ A1II u) is detected. The relative C2 fluorescence intensity and spectral patterns exhibited by each alkene are strongly dependent on the probe-laser wavelength. The dependence of the fragment fluorescence intensity on the probe-laser fluence implies that the “probe” laser induces photofragmentation of intermediate species produced by the “photolysis” laser.

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