Tight focusing of laser light using a chromium Fresnel zone plate
Date
21/08/2017Metadata
Show full item recordAbstract
Using near-field scanning microscopy, we demonstrate that a 15-µm zone plate fabricated in a 70-nm chromium film sputtered on a glass substrate and having a focal length and outermost zone's width equal to the incident wavelength λ = 532 nm, focuses a circularly polarized Gaussian beam into a circular subwavelength focal spot whose diameter at the full-width of half-maximum intensity is FWHM = 0.47λ. This value is in near-accurate agreement with the FDTD-aided numerical estimate of FWHM = 0.46λ. When focusing a Gaussian beam linearly polarized along the y-axis, an elliptic subwavelength focal spot is experimentally found to measure FWHMx = 0.42λ (estimated value FWHMx = 0.40λ) and FWHMy = 0.64λ. The subwavelength focal spots presented here are the tightest among all attained so far for homogeneously polarized beams by use of non-immersion amplitude zone plates.
Citation
Kotlyar , V V , Stafeev , S S , Nalimov , A G , Kotlyar , M V , O'Faolain , L & Kozlova , E S 2017 , ' Tight focusing of laser light using a chromium Fresnel zone plate ' , Optics Express , vol. 25 , no. 17 , pp. 19662-19671 . https://doi.org/10.1364/OE.25.019662
Publication
Optics Express
Status
Peer reviewed
ISSN
1094-4087Type
Journal article
Description
Funding: Russian Scientific Foundation (17-19-01186).Collections
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