High efficiency multilevel phase-type fractal zone plates
2008; Optica Publishing Group; Volume: 33; Issue: 24 Linguagem: Inglês
10.1364/ol.33.002913
ISSN1539-4794
AutoresDong Wu, Li‐Gang Niu, Qi‐Dai Chen, Rui Wang, Hong‐Bo Sun,
Tópico(s)Photonic Crystals and Applications
ResumoThree kinds of high efficiency phase-type fractal zone plates were rapidly (in tens of minutes) fabricated by femtosecond laser two-photon photopolymerization. Their theoretical maximal diffractive efficiencies of 24.5%, 12.52%, and 18.76% were predicted both by numerical simulation and analytical deduction and were verified by the measured values of 20.5%, 9.1%, and 13%, respectively. The characteristic of multifoci and the improved imaging ability for phase-type fractal lens was also demonstrated. Moreover, to further enhance the diffractive efficiency, a four-level fractal phase lens, whose diffraction efficiency reached as high as 37.6%, was proposed and realized.
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