Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses Guangjin Ma1,2, William Dallari1, Antonin Borot1, Ferenc Krausz1,3, Wei Yu2, George D. Tsakiris1, Laszlo Veisz1 1. Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany 2. Shanghai Institute of Optics and Fine Mechanics, 201800 Shanghai, China 3. Ludwig-Maximilians-UniversitaetMuenchen, Am Coulombwall 1, 85748 Garching, Germany E-mail:
[email protected]
Towards the goal of obtaining an intense isolated attosecond pulse through laser relativistic plasma interaction using the current existing few-cycle laser systems, both an investigation of the pertinent parameter space and an in depth understanding of the generation process are indispensable. In our work, we have explored a multidimensional variable space through 1D PIC simulations to find the optimum interaction conditions. Preplasma scale lengths as well as laser pulse intensity and carrier-envelope-phase (CEP) are varied to determine their optimum combinations. In addition to the well-known pivotal role played by the peak laser intensity, our results show that to efficiently generate an isolated attosecond pulse (fig. a) using state-of-the-art laser technology, preplasma scale length and CEP have to be optimized (Fig. b). Our study also shows that the conditions for optimal conversion efficiency coincide with those for the generation of an isolated attosecond pulse.
Fig 1. (a) Incident and reflected electric field and the resulting attosecond pulse in PIC simulation ( CEP 900 and L 0.25 ). (b) Harmonic conversion efficiency as function of preplasma scale length and CEP. In both (a) and (b), 20 2 laser intensity is fixed to be 2 10 W cm and harmonic order 10 to 50 are selected in forming attosecond pulse and calculating conversion efficiency.
In order to verify our simulation results and to get an in depth understanding of the generation process, a simple theoretical model is currently being developed. The preliminary results show good agreement between theory and simulation. References: [1] G. Ma, et al., “Optimized Conditions for Intense Isolated Attosecond Pulse Generation”, in 2013 European Conference on Lasers and Electro-Optics, paper CG_P_11. [2] G. D. Tsakiris et al., “Route to intense single attosecond pulses”, New J. Phys., 8,19(2006). [3] P. Heissler et al., “Few-Cycle Driven Relativistically Oscillating Plasma Mirrors: A Source of Intense Isolated Attosecond Pulses”, Phys. Rev. Lett. 108, 235003 (2012). 31
