Birefringent Fresnel zone plates in silica fabricated by femtosecond laser machining.
We demonstrate maskless, single-step fabrication of strongly birefringent Fresnel zone plates by focusing of femtosecond laser pulses deep within silica substrates. The process allows us to produce alternate zone rings directly by inducing a local refractive-index modification of the order of n~10(-2) . The embedded zone plates shown in this Letter exhibit efficiencies that vary by as much as a factor of ~6 for orthogonal polarizations. Focal lengths of primary and secondary foci are shown to compare well with theory.
Bricchi
Erica
E
Mills
John D
JD
Kazansky
Peter G
PG
Klappauf
Bruce G
BG
Baumberg
Jeremy J
JJ