High fill-factor multilevel Fresnel zone plate arrays by femtosecond laser direct writing

Fresnel zone plate arrays (FZPAs) as a kind of an important integrated micro-optical device have attracted great attention However the fill factor of present FZPAs by femtosecond technology is a little low which leads to serious light loss and low signal-to-noise Here we reported high fill-factor square and hexagonal FZPAs by femtosecond laser two-photon polymerization of the resin SU-8 Their optical focusing and imaging properties showed the high uniformity and high fidelity of these FZPAs Moreover 100% fill factor FZPAs were demonstrated by optimal theoretical design and experimental parameters With this high quality FZPAs clear imaging F' was obtained At last high level phase type FZPAs were prepared to further enhance the diffractive efficiency to as much as 75% (C) 2010 Elsevier B V All rights reserved