首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 62 毫秒
1.
Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study; the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of ω_1, ω_2 and ω_3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover,we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.  相似文献   

2.
罗牧华  张秋菊 《中国物理 B》2011,20(8):85201-085201
The influence of time-dependent polarization on attosecond pulse generation from an overdense plasma surface driven by laser pulse is discussed analytically and numerically.The results show that the frequency of controlling pulse controls the number and interval of the generated attosecond pulse,that the generation moment of the attosecond pulse is dominated by the phase difference between the controlling and driving pulses,and that the amplitude of the controlling pulse affects the intensity of the attosecond pulse.Using the method of time-dependent polarization,a "single" ultra-strong attosecond pulse with duration τ≈ 8.6 as and intensity I ≈ 3.08 × 10 20 W·cm-2 can be generated.  相似文献   

3.
A scheme of a single x-ray attosecond pulse generation from a two-atom system exposed to the combined laser pulses is proposed. Our numerical results show that a single x-ray attosecond pulse rather than a train one can be produced by modulation of ionization. Furthermore, when we change the peak intensity Ih of the high-frequency pulse and keep the intensity of the low-frequency pulse constant, we can find that a range of Ih where the intensity of the attosecond pulse is optimal is available, and a explanation by the stimulated property of the recombination is also presented.  相似文献   

4.
We present analytical studies of electron acceleration in the low-density preplasma of a thin solid target by an intense femtosecond laser pulse. Electrons in the preplasma are trapped and accelerated by the ponderomotive force as well as the wake field. Two-dimensional particle-in-cell simulations show that when the laser pulse is stopped by the target, electrons trapped in the laser pules can be extracted and move forward inertially. The energetic electron bunch in the bubble is unaffected by the reflected pulse and passes through the target with small energy spread and emittance. There is an optimal preplasma density for the generation of the monoenergetic electron bunch if a laser pulse is given. The maximum electron energy is inverse proportion to the preplasma density.  相似文献   

5.
We investigate the temperature dependence of the emission spectrum of a laser-induced semiconductor(Ge and Si) plasma. The change in spectral intensity with the sample temperature indicates the change of the laser ablation mass. The reflectivity of the target surface is reduced as the sample is heated, which leads to an increase in the laser energy coupled to the surface of the sample and eventually produces a higher spectral intensity.The spectral intensities are enhanced by a few times at high temperatures compared with the cases at low temperatures. The spectral intensity of Ge is enhanced by 1.5 times at 422.66 nm, and 3 times at589.33 nm when the sample temperature increases from 50°C to 300°C. We can obtain the same emission intensity by a more powerful laser or by less pulse energy with a higher sample temperature. Based on experimental observations we conclude that the preheated sample can improve the emission intensity of laser-induced semiconductor plasma spectroscopy.  相似文献   

6.
葛愉成 《中国物理 B》2008,17(6):2072-2077
This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.  相似文献   

7.
The paper has studied the influence of target material and thickness on energy and angular distributions of the protons generated by using an 800 nm,60 fs,0.24 J laser pulse to irradiate solid target foils.The results show that the initial density and thickness of the targets will affect the formation of the acceleration sheath fields in the target normal direction.For the same target thickness,using lower density target materials can obtain a higher proton maximum energy.However,lower density targets tend to be deformed due to the shock waves launched by the laser pulses,making the proton spatial distribution more divergent.  相似文献   

8.
张刚台  白婷婷  张美光 《中国物理 B》2012,21(5):54214-054214
We theoretically investigate high-order harmonic generation(HHG) from a helium ion model in a two-color laser field,which is synthesized by a fundamental pulse and its second harmonic pulse.It is shown that a supercontinuum spectrum can be generated in the two-color field.However,the spectral intensity is very low,limiting the application of the generated attosecond(as) pulse.By adding a static electric field to the synthesized two-color field,not only is the ionization yield of electrons contributing to the harmonic emission remarkably increased,but also the quantum paths of the HHG can be significantly modulated.As a result,the extension and enhancement of the supercontinuum spectrum are achieved,producing an intense isolated 26-as pulse with a bandwidth of about 170.5 eV.In particular,we also analyse the influence of the laser parameters on the ultrabroad supercontinuum spectrum and isolated sub-30-as pulse generation.  相似文献   

9.
The effect of the absolute phase of the few-cycle driving laser field on the generation and measurement of highorder harmonic attosecond pulses is investigated theoretically.We find that the generated attosecond soft-x-ray pulse is locked to the oscillations of the driving laser field,but not to the envelope of the laser pulse,and the intensity ratio of two adjacent attosenond pulses is exponential as a function of the absolute phase.Based on these results,we propose a novel method to detect the absolute phase of the driving laser field by measuring the spatial distribution of the photoelectrons induced by the attosecond soft-x-ray pulse and the driving laser field.  相似文献   

10.
In conventional pulsed laser deposition(PLD) technique, plume deflection and composition distribution change with the laser incident direction and pulse energy, then causing uneven film thickness and composition distribution for a multicomponent film and eventually leading to low device quality and low rate of final products. We present a novel method based on PLD for depositing large CIGS films with uniform thickness and stoichiometry. By oscillating a mirror placed coaxially with the incident laser beam,the laser's focus is scanned across the rotating target surface. This arrangement maintains a constant reflectance and optical distance, ensuring that a consistent energy density is delivered to the target surface by each laser pulse. Scanning the laser spot across the target suppresses the formation of micro-columns, and thus the plume deflection effect that reduces film uniformity in conventional PLD technique is eliminated.This coaxial scanning PLD method is used to deposit a CIGS film, 500 nm thick, with thickness uniformity exceeding ±3% within a 5 cm diameter, and exhibiting a highly homogeneous elemental distribution.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号