Study of focal shift effect in planar GaN high contrast grating lenses

Shumin He, Zhenhai Wang, Qifa Liu, Wei Wang

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


In this paper, systematical study on the focal shift phenomenon in planar lenses based on GaN high contrast gratings was performed using finite element method (FEM). Influence of parameters including device size, designed focal length, total phase difference on the focusing performance is presented. It shows that the focal shift is mainly determined by the Fresnel number of the lens, which is nearly equal to the total phase difference divided by φ. The influence of the lens size and designed focal length can be attributed to the change of Fresnel number. Theoretical analysis based on diffraction theory is employed to predict the focal shift, which is in accordance with the numerical simulation.

Original languageEnglish
Pages (from-to)29360-29638
Number of pages279
JournalOptics Express
Issue number23
Publication statusPublished - 16 Nov 2015
Externally publishedYes


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