Three-dimensional circular spiral photonic crystal structures recorded by femtosecond pulses

Photonic crystal structures having three-dimensional (3D) circular spiral architecture have large theoretical photonic band-gap but cannot be implemented by most of the existing microfabrication techniques. We have successfully used a highly versatile 3D microstructuring technique called femtosecond laser microfabrication to prepare templates of the circular spiral photonic crystals in a commercially available photoresist SU-8. The structures fabricated have good structural quality, are highly periodic and exhibit spectral signatures of photonic bands dispersion in the short infrared wavelength region.