Light Sources and FELs
Tech 24: Lasers
Paper Title Page
THP222 Drive Laser System for the Advanced Photo-Injector Project at the LBNL 2537
 
  • J. Feng, D. Filippetto, H.A. Padmore, F. Sannibale, R.P. Wells
    LBNL, Berkeley, California, USA
  • M. J. Messerly, M.A. Prantil
    LLNL, Livermore, California, USA
 
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The electron photo-gun of the Advanced Photo-injector EXperiment project (APEX) at the LBNL will be driven by a compact fiber laser for different photo-cathode experiments during the initial phase of the project. The fiber laser, developed at the Lawrence Livermore National Laboratory, is designed to deliver μJ/pulse at 1064 nm system that is frequency doubled to deliver light at 532nm with 1MHz repetition rate and 1ps pulse length optimized for photo-emission with multi-alkali antimonide cathodes. For Cs2Te and diamond amplifier cathodes, the 4th harmonic will be generated by doubling frequency again in a non-linear crystal. Due to the requirement of small emittance for the electron beam, the laser pulse will be shaped in space and time for 532nm and UV lights, in general with a constant intensity in cross section with a sharp radial cutoff, and elliptical or rectangular distribution in the longitudinal plane. Diagnostics of the laser beam itself and of the cathode will be integrated with techniques such as cross- correlation, streak camera, and virtual cathode imaging, not only to monitor the laser pulse but also to provide automated feedbacks.
 
 
THP223 Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source 2540
 
  • D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly
    LLNL, Livermore, California, USA
 
  Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.
 
 
THP224 Progress Report on Development of Novel Ultrafast Mid-IR Laser System 2543
 
  • R. Tikhoplav, A.Y. Murokh
    RadiaBeam, Santa Monica, USA
  • I. Jovanovic
    Penn State University, University Park, Pennsylvania, USA
 
  Of particular interest to X-ray FEL light source facilities is Enhanced Self-Amplified Spontaneous Emission (ESASE) technique. Such a technique requires an ultrafast (20-50 fs) high peak power, high repetition rate reliable laser systems working in the mid-IR range of spectrum (2μm or more). The approach of this proposed work is to design a novel Ultrafast Mid-IR Laser System based on optical parametric chirped-pulse amplification (OPCPA). OPCPA is a technique ideally suited for production of ultrashort laser pulses at the center wavelength of 2 μm. Some of the key features of OPCPA are the wavelength agility, broad spectral bandwidth and negligible thermal load. This paper reports on the progress of the development of the Ultrafast Mid-IR Laser System.  
 
THP225 Characterization and Suppression of the Electromagnetic Interference Induced Phase Shift in the JLab FEL Photo – Injector Advanced Drive Laser System 2546
 
  • F.G. Wilson, D.W. Sexton, S. Zhang
    JLAB, Newport News, Virginia, USA
 
  The new drive laser for the photo-cathode gun used in the JLab FEL facility had been experiencing various phase shifts on the order of tens of degrees (>20° at 1497 MHz or >40ps) when changing the Advanced Drive Laser (ADL) micro-pulse frequencies. These phase shifts introduce multiple complications when trying to setup the accelerator for operation, ultimately inhibiting the robustness and overall performance of the FEL. Through rigorous phase measurements and systematic characterizations, we discovered the problems could be attributed to EMI coupling into the ADL phase control loop system, and subsequently resolved the issue of phase shift to within tenths of a degree (<0.5° at 1497 MHz or <1ps). The diagnostic method developed and the knowledge gained through the entire process will prove to be invaluable for future designs of similar systems.