Nanofocusing of longitudinally polarized light using absorbance modulation
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education of China, Nankai University, Tianjin 300071 (China)
- Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)
Recently, many methods based on amplitude or phase modulation to reduce the focal spot and enhance the longitudinal field component of a tight-focused radially polarized light beam have been suggested. But they all suffer from spot size limit 0.36λ/NA and large side lobes strength in longitudinal component. Here, we report a method of generating a tighter focused spot by focusing radially polarized and azimuthally polarized beams of different wavelengths on a thin photochromic film through a high-numerical-aperture lens simultaneously. In this method, by suppressing the radial component and compressing the longitudinal component of radially polarized beam, absorbance modulation makes the ultimate spot size break the size limit of 0.36λ/NA with side-lobe intensity of longitudinal component below 1% of central-peak intensity. The theoretical analysis and simulation demonstrate that the focal spot size could be smaller than 0.1λ with nearly all radial component blocked at high intensity ratio of the two illuminating beams.
- OSTI ID:
- 22283185
- Journal Information:
- Applied Physics Letters, Vol. 104, Issue 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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