Accelerating electrons with lasers and photonic crystals

摘要

We present work done towards the successful fabrication of a four-layer woodpile photonic crystal with a bandgap of 0.876 mu m centered at 4.55 mu m. The goal of this fabrication was to develop a process flow that will be used to fabricate a 15-layer woodpile structure with a defect used for accelerating electrons. The structure dimensions were designed using simulations to maximize the bandgap, and scaled by the minimum features achievable in the optical lithography process. Infrared spectroscopy measurements were taken of the resulting four-layer structure, demonstrating a clear bandgap region centered at 4.55 mu m, with a full-width at half maximum (FWHM) of 2.72 mu m. Variations in the actual fabricated structure were measured via SEM images, and the deviations were incorporated into simulations. The center bandgap wavelength predicted in simulations agrees to within 1% of the measured value, and the FWHM agrees to within 15% of the measurement. These results provide validation for the quality of the photonic crystal fabricated.