scholarly journals Detecting electronic coherences by time-domain high-harmonic spectroscopy

2020 ◽  
Vol 117 (18) ◽  
pp. 9776-9781 ◽  
Author(s):  
Shicheng Jiang ◽  
Konstantin Dorfman
Keyword(s):  
Time Domain ◽  
High Harmonic ◽  
Electronic States ◽  
High Order ◽  
Laser Source ◽  
X Ray ◽  
Liouville Space ◽  
High Order Harmonic ◽  
Multiple Pulses ◽  
The Time Domain

Ultrafast spectroscopy is capable of monitoring electronic and vibrational states. For electronic states a few eV apart, an X-ray laser source is required. We propose an alternative method based on the time-domain high-order harmonic spectroscopy where a coherent superposition of the electronic states is first prepared by the strong optical laser pulse. The coherent dynamics can then be probed by the higher-order harmonics generated by the delayed probe pulse. The high nonlinearity typically modeled by the three-step mechanism introduced by Lewenstein and Corkum can serve as a recipe for generation of the coherent excitation with broad bandwidth. The main advantage of the method is that only optical (non–X-ray) lasers are needed. A semiperturbative model based on the Liouville space superoperator approach is developed for the bookkeeping of the different orders of the nonlinear response for the high-order harmonic generation using multiple pulses. Coherence between bound electronic states is monitored in the harmonic spectra from both first- and second-order responses.

scholarly journals Bright High-Order Harmonic Generation around 30 nm Using Hundred-Terawatt-Level Laser System for Seeding Full Coherent XFEL

2018 ◽  
Vol 8 (9) ◽  
pp. 1446 ◽  
Author(s):  
Luyao Zhang ◽  
Yinghui Zheng ◽  
Guicun Li ◽  
Zhengmao Jia ◽  
Yanyan Li ◽  
...  
Keyword(s):  
Harmonic Generation ◽  
Beam Quality ◽  
Laser System ◽  
High Harmonic ◽  
High Order ◽  
Laser Source ◽  
High Order Harmonic Generation ◽  
X Ray ◽  
High Order Harmonic ◽  
Level Laser

In the past few years, the laser wakefield acceleration (LWFA) electron is a hot topic. One of its applications is to produce soft X-ray free-electron laser (XFEL). During this process, high harmonic generation (HHG) is a potential seed. To decrease the timing jitter between LWFA and HHG, it is better for them to come from the same laser source. We have experimentally investigated bright high-order harmonic generation with a 200-terawatt (TW)/1-Hz Ti: Sapphire laser system. By using the loosely focused method and optimizing the phase-matching conditions, we have obtained bright high-order harmonics around 30 nm. Output energy of the 29th harmonic (27.6 nm) reaches as high as 100 nJ per pulse, and the harmonic beam divergence is estimated to be 0.3 mrad in a full width at half maximum (FWHM). Although the hundred-TW-level laser system has the problems of poor beam quality and shot-to-shot energy fluctuation for HHG, the generated soft X-ray (~30 nm) sources can also have good stability by carefully optimizing the laser system.

Numerical simulations of time-domain interferometric soft X-ray microscope with broadband high-order harmonic light sources

2013 ◽  
Vol 102 (7) ◽  
pp. 071102 ◽  
Author(s):  
Reika Kanya ◽  
Atsushi Iwasaki ◽  
Takahiro Teramoto ◽  
Kaoru Yamanouchi
Keyword(s):  
Numerical Simulations ◽  
Time Domain ◽  
High Order ◽  
Light Sources ◽  
X Ray ◽  
High Order Harmonic

The effect of initial phase on the emission characteristics of forward electron colliding with a tightly focused linearly polarized few-cycle laser pulse

Laser Physics ◽  
2021 ◽  
Vol 32 (2) ◽  
pp. 025001
Author(s):  
XingKang Li ◽  
Shuwen Mao ◽  
Penghang Yu ◽  
JianPing Chang ◽  
Youwei Tian
Keyword(s):  
Laser Pulse ◽  
Strong Field ◽  
High Harmonic ◽  
Potential Method ◽  
Harmonic Spectrum ◽  
X Ray ◽  
High Order Harmonic ◽  
Linearly Polarized ◽  
The Time Domain ◽  
The Relationship

Abstract We have studied the high harmonic radiation property from the scattering of an electron with a focused few-cycle laser pulse by analyzing the distribution of the radiation field and the motion state of the electron. In the time domain, temporal width of the compressed radiation can reach 33 zs (zeptosecond), thus an ultrashort x-ray pulse was generated in the interaction process. The radiation in this process is vastly similar to high harmonic generation in the process of atomic strong-field. The latter depends to a large extent on the phase of carrier-envelope (CE) driving laser pulse. The cutoff of radiation spectrum can reach 1 × 10 5 ω 0 , and whether the high-order harmonic spectrum in the cut-off region can be well resolved depends on the CE phase. We have investigated the relationship between the maximum radiation intensity and the CE phase, and discussed a potential method to characterize the CE phase of an intense few-cycle laser pulse for broader application prospects.

scholarly journals Reconstruction algorithm for tunneling ionization with a perturbation for the time-domain observation of an electric-field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wosik Cho ◽  
Jeong-uk Shin ◽  
Kyung Taec Kim
Keyword(s):  
Laser Pulse ◽  
Electric Field ◽  
Time Domain ◽  
Reconstruction Algorithm ◽  
High Order ◽  
Reconstruction Process ◽  
Tunneling Ionization ◽  
Order Contribution ◽  
High Order Contribution ◽  
The Time Domain

AbstractWe present a reconstruction algorithm developed for the temporal characterization method called tunneling ionization with a perturbation for the time-domain observation of an electric field (TIPTOE). The reconstruction algorithm considers the high-order contribution of an additional laser pulse to ionization, enabling the use of an intense additional laser pulse. Therefore, the signal-to-noise ratio of the TIPTOE measurement is improved by at least one order of magnitude compared to the first-order approximation. In addition, the high-order contribution provides additional information regarding the pulse envelope. The reconstruction algorithm was tested with ionization yields obtained by solving the time-dependent Schrödinger equation. The optimal conditions for accurate reconstruction were analyzed. The reconstruction algorithm was also tested using experimental data obtained using few-cycle laser pulses. The reconstructed pulses obtained under different dispersion conditions exhibited good consistency. These results confirm the validity and accuracy of the reconstruction process.

scholarly journals Beating absorption in solid-state high harmonics

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hanzhe Liu ◽  
Giulio Vampa ◽  
Jingyuan Linda Zhang ◽  
Yu Shi ◽  
Siddharth Buddhiraju ◽  
...  
Keyword(s):  
Vacuum Ultraviolet ◽  
Crystalline Silicon ◽  
High Harmonic ◽  
Ultra Violet ◽  
Fold Increase ◽  
High Energy ◽  
High Order ◽  
Limiting Factor ◽  
X Ray ◽  
On Chip

Abstract Since the new millennium coherent extreme ultra-violet and soft x-ray radiation has revolutionized the understanding of dynamical physical, chemical and biological systems at the electron’s natural timescale. Unfortunately, coherent laser-based upconversion of infrared photons to vacuum-ultraviolet and soft x-ray high-order harmonics in gaseous, liquid and solid targets is notoriously inefficient. In dense nonlinear media, the limiting factor is strong re-absorption of the generated high-energy photons. Here we overcome this limitation by generating high-order harmonics from a periodic array of thin one-dimensional crystalline silicon ridge waveguides. Adding vacuum gaps between the ridges avoids the high absorption loss of the bulk and results in a ~ 100-fold increase of the extraction depth. As the grating period is varied, each high harmonic shows a different and marked modulation, indicating their waveguiding in the vacuum slots with reduced absorption. Looking ahead, our results enable bright on-chip coherent short-wavelength sources and may extend the usable spectral range of traditional nonlinear crystals to their absorption windows. Potential applications include on-chip chemically-sensitive spectro-nanoscopy.

Sign in / Sign up

Export Citation Format

Share Document