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Focusing of elliptically polarized Gaussian beams through an annular high numerical aperture
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作者 陈宝算 蒲继雄 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第7期245-250,共6页
Based on the vectorial Debye theory, the focusing properties of the Gaussian beam through an annular high numerical aperture are studied numerically, including the intensity, the phase and the orbital angular momentum... Based on the vectorial Debye theory, the focusing properties of the Gaussian beam through an annular high numerical aperture are studied numerically, including the intensity, the phase and the orbital angular momentum properties. Then the influence of certain parameters on the focusing properties is also investigated. It is shown that sub-wavelength elliptical light spots can be obtained. And there exists a vortex in the longitudinal component of the focused field even though the incident beam is Gaussian beam, indicating that the spin angular momentum of the elliptically polarized Gaussian beam is converted into the orbital angular momentum by the focusing. 展开更多
关键词 Debye theory high numerical aperture elliptically polarized FOCUSING
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Deep-subwavelength single grooves prepared by femtosecond laser direct writing on Si
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作者 叶瑞熙 黄敏 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期108-115,共8页
It is well known that femtosecond laser pulses can easily spontaneously induce deep-subwavelength periodic surface structures on transparent dielectrics but not on non-transparent semiconductors.Nevertheless,in this s... It is well known that femtosecond laser pulses can easily spontaneously induce deep-subwavelength periodic surface structures on transparent dielectrics but not on non-transparent semiconductors.Nevertheless,in this study,we demonstrate that using high-numerical-aperture 800 nm femtosecond laser direct writing with controlled pulse energy and scanning speed in the near-damage-threshold regime,polarization-dependent deep-subwavelength single grooves with linewidths of~180 nm can be controllably prepared on Si.Generally,the single-groove linewidth increases slightly with increase in the pulse energy and decrease in the scanning speed,whereas the single-groove depth significantly increases from~300 nm to~600 nm with decrease in the scanning speed,or even to over 1μm with multi-processing,indicating the characteristics of transverse clamping and longitudinal growth of such deep-subwavelength single grooves.Energy dispersive spectroscopy composition analysis of the near-groove region confirms that single-groove formation tends to be an ultrafast,non-thermal ablation process,and the oxidized deposits near the grooves are easy to clean up.Furthermore,the results,showing both the strong dependence of groove orientation on laser polarization and the occurrence of double-groove structures due to the interference of pre-formed orthogonal grooves,indicate that the extraordinary field enhancement of strong polarization sensitivity in the deep-subwavelength groove plays an important role in single-groove growth with high stability and collimation. 展开更多
关键词 femtosecond-laser direct writing of Si deep-subwavelength single grooves polarization dependence high numerical aperture ultrafast non-thermal ablation
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Experimental research on the longitudinal field generated by a tightly focused beam 被引量:1
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作者 张明倩 王佳 田芊 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第4期258-263,共6页
The longitudinal optical field is a peculiar physical phenomenon that is always involved with the domain of near-field optics. Due to its extraordinary properties, it has recently attracted increasing attention in res... The longitudinal optical field is a peculiar physical phenomenon that is always involved with the domain of near-field optics. Due to its extraordinary properties, it has recently attracted increasing attention in research and application. In this work, the longitudinal fields generated by the evanescent illumination of tightly focused, different polarized hollow beams are investigated. The focused light fields are numerically simulated according to vector diffraction theory, and their vector analysis is also carried out. The longitudinal fields on the focal plane are demonstrated experimentally using tip-enhanced scanning near-field microscopy. The simulation and experimental results show that the tightly focused radially polarized beam is suited to generating a stronger and purer longitudinal optical field at the focus. 展开更多
关键词 longitudinal optical field high numerical aperture focusing beam POLARIZATION
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Tight focusing of partially polarized vortex beams by binary phase Fresnel zone plates 被引量:1
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作者 舒建华 陈子阳 +1 位作者 蒲继雄 刘永欣 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第11期248-254,共7页
Based on vectorial Debye theory, the focusing properties of partially polarized vortex beam by high numerical aperture Fresnel zone plate are investigated. The effects of the numerical apertures of and the phase diffe... Based on vectorial Debye theory, the focusing properties of partially polarized vortex beam by high numerical aperture Fresnel zone plate are investigated. The effects of the numerical apertures of and the phase difference of binary phase Fresnel zone plates, the topological charge of vortex beam and the degree of polarization of incident beam on the intensity distribution and degree of coherence in the focal plane are investigated in detail. It is shown that elliptical light spots and the flat top beam can be obtained by selecting certain parameters. Studies of degree of coherence reveal that the degree of coherence between x and y components of the electric field, which is zero in the source plane, is improved in the focal plane for vortex beam, but it is hardly changed for the nonvortex beam. It is also proved that any two of the three electric field components Ex, Ey and Ez are completely coherent everywhere in the focal region if the incident light beam is linearly polarized. 展开更多
关键词 partially polarized vortex beams high numerical aperture binary phase Fresnel zoneplates
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Generation of wavelength-independent subwavelength Bessel beams using metasurfaces 被引量:4
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作者 Wei Ting Chen Mohammadreza Khorasaninejad +4 位作者 Alexander Y.Zhu Jaewon Oh Robert C.Devlin Aun Zaidi Federico Capasso 《Light(Science & Applications)》 SCIE EI CAS CSCD 2016年第1期39-44,共6页
Bessel beams are of great interest due to their unique non-diffractive properties.Using a conical prism or an objective paired with an annular aperture are two typical approaches for generating zeroth-order Bessel bea... Bessel beams are of great interest due to their unique non-diffractive properties.Using a conical prism or an objective paired with an annular aperture are two typical approaches for generating zeroth-order Bessel beams.However,the former approach has a limited numerical aperture(NA),and the latter suffers from low efficiency,as most of the incident light is blocked by the aperture.Furthermore,an additional phase-modulating element is needed to generate higher-order Bessel beams,which in turn adds complexity and bulkiness to the system.We overcome these problems using dielectric metasurfaces to realize meta-axicons with additional functionalities not achievable with conventional means.We demonstrate meta-axicons with high NA up to 0.9 capable of generating Bessel beams with full width at half maximum about as small as~λ/3(λ=405 nm).Importantly,these Bessel beams have transverse intensity profiles independent of wavelength across the visible spectrum.These meta-axicons can enable advanced research and applications related to Bessel beams,such as laser fabrication,imaging and optical manipulation. 展开更多
关键词 Bessel beam high numerical aperture light angular momentum metasurface
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