WEA2WC —  WG-C   (07-Mar-18   11:00—12:30)
Chair: H. Zen, Kyoto University, Kyoto, Japan
Paper Title Page
CEP-Stabilized Few-cycle MIR-FELs for Driving High-Repetition-Rate (>10 MHz) Attosecond X-ray Sources Based on HHG  
  • R. Hajima
    QST, Tokai, Japan
  Funding: This research was partially supported by the Research Foundation for Opto-Science and Technology.
High harmonic generation (HHG) is a well-established technology to produce attosecond pulses in VUV wavelengths. So far HHG sources have been driven by femtosecond solid-state lasers not FELs, because it has been believed that FELs have no ability to provide carrier-envelope-phase (CEP) stabilized few-cycle pulses essential to the HHG. Here, we propose a scheme to CEP stabilized few-cycle pulses from a FEL oscillator. Operated at a mid-infrared wavelength, the proposed method is able to drive a HHG photon source to produce isolated attosecond pulses at photon energies above 1 keV with a repetition > 10 MHz. The FEL-HHG photon source will open a door to full-scale experiments of attosecond X-ray pulses and push ultrafast laser science to the zeptosecond regime [1].
[1] R. Hajima and R. Nagai, Phys. Rev. Lett. 119, 204802 (2017)
slides icon Slides WEA2WC01 [3.451 MB]  
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High-efficient XFELO Based on Optical Resonator with Self-modulated Q-factor  
  • C.-J. Jing, S.P. Antipov
    Euclid Beamlabs LLC, Bolingbrook, USA
  • S.P. Antipov
    ANL, Argonne, Illinois, USA
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S.V. Kuzikov, A.V. Savilov
    IAP/RAS, Nizhny Novgorod, Russia
  • A.V. Savilov
    UNN, Nizhny Novgorod, Russia
  We suggest an efficient XFELO having a new non-stationary out-coupling scheme. It consisted of two undulator sections located in sequence with a free space gap in-between. The first section is a conventional uniform undulator, the second one is a tapered undulator. At start time point X-ray radiation is basically produced by the uniform section. Mirrors of XFELO's optical resonator are calculated so that diffraction Q-factor reaches the highest value, i.e losses asre near to zero. As X-ray power increases the tapered undulator begins to bring more contribution in radiation power. Finally, at a new steady state regime all power is being produced by the tapered section. Because mirrors were optimized for Gaussian wavebeam to be produced in the first section, in the final steady state regime a portion of X-ray power will be out-coupled missing partly the mirrors.  
slides icon Slides WEA2WC02 [4.298 MB]  
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A 1d Time-Dependent Theoretical Model of X-Ray Free-Electron Laser Oscillator  
  • K. Li, H.X. Deng
    SINAP, Shanghai, People's Republic of China
  FEL is a cutting-edge tool for generating high brilliant, wavelength adjustable radiation. FEL oscillators (FELO) is one of FEL's operation mode. A novel simplified theoretical model for fast simulation and optimization of FELO is proposed. Instead of utilizing conventional macro particles tracking, i.e., GENESIS and OPC codes, the theoretical model takes advantage of low-gain theory to calculate single-pass gain analytically and it is able to considerably reduce calculation time, i.e., from several days to a few minutes. In addition, it is useful for simulating new FELO scheme such as gain cascading.  
slides icon Slides WEA2WC03 [2.503 MB]  
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