Fwd: University PhD Dissertation Defense of Christopher Michael McGuinness

Department of Applied Physics

University PhD Dissertation Defense

 

Particle Accelerator on a Chip:

Fabrication and Characterization of a Three-Dimensional Photonic Crystal Accelertor

 

Christopher Michael McGuinness

Research Advisor: Professor Robert Byer

 

Friday, May 11, 2012 @10:00 A.M.

Location: Allen Building (Formerly CIS-X), Room 101

ABSTRACT

Charged particles are currently accelerated by microwave radiation generated in large klystrons. This is very reminiscent of vacuum tube diodes on which early computers relied. Can particle accelerator technology follow the shift that drove the semiconductor industry from vacuum tubes to solid state devices? Can particle accelerators benefit from the high energy density provided by lasers at optical and infrared wavelengths? Can dielectric materials replace the metallic waveguides allowing us to utilize the high peak powers available in lasers today?

In making this jump from microwave to infrared wavelengths, a decrease of 10,000 times in wavelength, entirely new fabrication technologies are needed. And entirely new physics must be applied in transitioning from metals to dielectrics. This talk will focus on the fabrication of photonic crystals designed for accelerating electrons. You will be introduced to a process for fabricating a three dimensional photonic crystal; the woodpile structure, designed to operate at mid-infrared wavelengths in the three to five micron range. Preliminary characterization of these structures was performed using Fourier transform infrared spectroscopy, and comparison with simulations show good agreement when the structure parameters are modeled appropriately. Attempts have been made to couple light from a tunable optical parametric oscillator into a waveguide designed to support an accelerator mode. Finally, an alternative fabrication approach has been pursued at the University of Karlsruhe in Germany based on direct laser writing. FTIR measurements show the first signs of a defect mode in one of these structures. Simulations were performed to analyze these measurements.