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Generation of a sub-diffraction hollow ring by shaping an azimuthally polarized wave

View Article: PubMed Central - PubMed

ABSTRACT

The generation of a sub-diffraction optical hollow ring is of great interest in various applications, such as optical microscopy, optical tweezers, and nanolithography. Azimuthally polarized light is a good candidate for creating an optical hollow ring structure. Various of methods have been proposed theoretically for generation of sub-wavelength hollow ring by focusing azimuthally polarized light, but without experimental demonstrations, especially for sub-diffraction focusing. Super-oscillation is a promising approach for shaping sub-diffraction optical focusing. In this paper, a planar sub-diffraction diffractive lens is proposed, which has an ultra-long focal length of 600 λ and small numerical aperture of 0.64. A sub-diffraction hollow ring is experimentally created by shaping an azimuthally polarized wave. The full-width-at-half-maximum of the hollow ring is 0.61 λ, which is smaller than the lens diffraction limit 0.78 λ, and the observed largest sidelobe intensity is only 10% of the peak intensity.

No MeSH data available.


(a) Generation of a sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens, and (b) the micro lens structure.
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f1: (a) Generation of a sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens, and (b) the micro lens structure.

Mentions: Figure 1(a) illustrates the generation of the sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens. The geometrical structure of the lens is depicted in Fig. 1(b). The lens consists of a series of concentric Si3N4 rings grown on the top of a glass substrate. The width and the thickness of the rings are T and t, respectively. The binary phase was realized by controlling the Si3N4 stripe thickness 0 and t for the phase changes of 0 and π, respectively. The value of t was obtained by t = λ/2(nSi3N4-1), with nSi3N4 being the refractive index of Si3N4.


Generation of a sub-diffraction hollow ring by shaping an azimuthally polarized wave
(a) Generation of a sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens, and (b) the micro lens structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120339&req=5

f1: (a) Generation of a sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens, and (b) the micro lens structure.
Mentions: Figure 1(a) illustrates the generation of the sub-diffraction hollow ring by shaping the azimuthally polarized wave with a planar binary phase lens. The geometrical structure of the lens is depicted in Fig. 1(b). The lens consists of a series of concentric Si3N4 rings grown on the top of a glass substrate. The width and the thickness of the rings are T and t, respectively. The binary phase was realized by controlling the Si3N4 stripe thickness 0 and t for the phase changes of 0 and π, respectively. The value of t was obtained by t = λ/2(nSi3N4-1), with nSi3N4 being the refractive index of Si3N4.

View Article: PubMed Central - PubMed

ABSTRACT

The generation of a sub-diffraction optical hollow ring is of great interest in various applications, such as optical microscopy, optical tweezers, and nanolithography. Azimuthally polarized light is a good candidate for creating an optical hollow ring structure. Various of methods have been proposed theoretically for generation of sub-wavelength hollow ring by focusing azimuthally polarized light, but without experimental demonstrations, especially for sub-diffraction focusing. Super-oscillation is a promising approach for shaping sub-diffraction optical focusing. In this paper, a planar sub-diffraction diffractive lens is proposed, which has an ultra-long focal length of 600 λ and small numerical aperture of 0.64. A sub-diffraction hollow ring is experimentally created by shaping an azimuthally polarized wave. The full-width-at-half-maximum of the hollow ring is 0.61 λ, which is smaller than the lens diffraction limit 0.78 λ, and the observed largest sidelobe intensity is only 10% of the peak intensity.

No MeSH data available.