• R.J. England, E.R. Colby, C. McGuinness, R.J. Noble, R. Siemann, J.E. Spencer, D.R. Walz
  SLAC, Menlo Park, California
• R. Ischebeck
  PSI, Villigen
• T. Plettner
  Stanford University, Stanford, California
• C.M.S. Sears
  MPQ, Garching, Munich

Funding: DOE Grants DE-AC02-76SF00515, DE-FG06-97ER41276

An experimental effort is currently underway at the SLAC National Accelerator Laboratory to focus a 50pC, 60 MeV electron beam into the hollow core of a commercial photonic bandgap fiber. The wakefield radiation produced in the fiber will be spectrally analyzed using a spectrograph in order to detect the frequency signatures of fiber modes that could be used as accelerating modes in a laser-driven fiber-based accelerator scheme. We discuss the current status of the experiment, including efforts to successfully focus the electron beam through the fiber aperture and to collect the produced wakefield radiation.

• C. McGuinness
  SLAC, Menlo Park, California

We present recent progress in the fabrication of a 3D photonic crystal laser accelerator structure. Direct acceleration of electrons by lasers offer promising improvements over traditional RF acceleration techniques in terms of cost, gradient, technology used, and short temporal bunches produced. Microbunching and net acceleration experiments were successfully performed at the E163 facility at SLAC, setting the stage for design, fabrication, and testing of optical structures. This paper describes work done at the Stanford Nanofabrication Facility towards fabricating such structures. A process based on standard optical lithographic techniques was used to fabricate a four layer woodpile photonic crystal with a bandgap centered at 4.55μm and a full width half max of 2.71μm. Infrared spectroscopy measurements were taken and compared with simulations yielding good agreement. SEM images were used to measure fabrication deviations in rod width, rod shape, layer thickness, and alignment, and further simulations are being done to study the effect of these deviations on properties of the accelerating mode excited in the defect of a 20 layer structure currently under design.