Propagation characteristics of silver and tungsten subwavelength annular aperture generated sub-micron non-diffraction beams
| Autor: | Chau-Shioung Yeh, Ding-Zheng Lin, Chih-Kung Lee, Tsung-Dar Cheng, Jonq-Min Liu, Jyi-Tyan Yeh |
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| Rok vydání: | 2009 |
| Předmět: |
Diffraction
Materials science Silver Light Extraordinary optical transmission Sensitivity and Specificity Tungsten Axicon Optics Focal length Nanotechnology Scattering Radiation business.industry Reproducibility of Results Equipment Design Surface Plasmon Resonance Polarization (waves) Surface plasmon polariton Atomic and Molecular Physics and Optics Nanostructures Equipment Failure Analysis Refractometry Optical tweezers Computer-Aided Design business Beam (structure) |
| Zdroj: | Optics express. 17(7) |
| ISSN: | 1094-4087 |
| Popis: | We examined the optical properties such as propagation modes, focal length, side lobes, etc. of metallic subwavelength annular apertures (SAA) and used finite-difference time-domain (FDTD) simulation to compare our experimental findings. Using two different metals, silver and tungsten, we examined the different optical transmission properties of the two metallic SAA structures. The far-field propagation of the silver SAA structure was found to be a type of quasi-Bessel beam when compared with a quasi-Bessel beam generated by a perfect axicon. The propagation characteristics of these two beams were found to match qualitatively. The far-field transmitted light generated by the silver SAA structure was found to possess a 390 nm sub-micron focal spot with a 24 microm depth of focus, which was much smaller than the focal spot generated by a perfect axicon. We also found that a silver SAA structure can generate a sub-micron quasi- Bessel beam that has a much lower far-field side-lobe when compared to that of non-diffraction beams generated by a tungsten SAA structure. |
| Databáze: | OpenAIRE |
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