headerpos: 12198
 
 
 

Proceedings of the Estonian Academy of Sciences

ISSN 1736-7530 (electronic)   ISSN 1736-6046 (print)
Formerly: Proceedings of the Estonian Academy of Sciences, series Physics & Mathematics and  Chemistry
Published since 1952

Proceedings of the Estonian Academy of Sciences

ISSN 1736-7530 (electronic)   ISSN 1736-6046 (print)
Formerly: Proceedings of the Estonian Academy of Sciences, series Physics & Mathematics and  Chemistry
Published since 1952
Publisher
Journal Information
» Editorial Board
» Editorial Policy
» Archival Policy
» Article Publication Charges
» Copyright and Licensing Policy
Guidelines for Authors
» For Authors
» Instructions to Authors
» LaTex style files
Guidelines for Reviewers
» For Reviewers
» Review Form
Open Access
List of Issues
» 2018
» 2017
Vol. 66, Issue 4
Vol. 66, Issue 3
Vol. 66, Issue 2
Vol. 66, Issue 1
» 2016
» 2015
» 2014
» 2013
» 2012
» 2011
» 2010
» 2009
» 2008
» Back Issues Phys. Math.
» Back Issues Chemistry
» Back issues (full texts)
  in Google. Phys. Math.
» Back issues (full texts)
  in Google. Chemistry
» Back issues (full texts)
  in Google Engineering
» Back issues (full texts)
  in Google Ecology
» Back issues in ETERA Füüsika, Matemaatika jt
Subscription Information
» Prices
Internet Links
Support & Contact
Publisher
» Staff
» Other journals

Numerical simulation of light propagation in metal-coated SNOM tips; pp. 430–436

(Full article in PDF format) https://doi.org/10.3176/proc.2017.4.12


Authors

Ardi Loot, Viktor Palm, Vladimir Hizhnyakov

Abstract

Presented are the results of numerical simulations accomplished to investigate the propagation of electromagnetic excitations in certain types of metal-coated tapered tips terminating SiO2 multimode optical fibres with a subwavelength output aperture. The numerical simulations were initiated in order to enable better interpretation of previously reported experimental results concerning some features of the mesoscopic effect of spectral modulation observed for a broadband light transmitted by such tips. This effect occurs due to the interference between a small number of waveguide modes exiting a metal-coated tip, and the experimental results indicate a possible mode-selective photon-plasmon coupling in the studied tips. To match the experimental conditions, the tips were modelled for the light wavelength of 800 nm as three-layer systems (with the intermediate adhesion Cr layer and the outer layer of Al or Au). However, due to computational restrictions the end of a tip, only 18 μm long (most significant), was modelled. Numerical simulations yielded the dependences of propagation and attenuation constants on the fibre core radius for the most intensive (both photonic and plasmonic) output modes. The pairs of modes most probably contributing to the observed spectral modulation were identified. Although the simulations did not reveal any explicit mode coupling, the imperfections of real tips can cause mode transformations implying possible involvement of more than two modes. The thin (20 nm) Cr layer plays the main role for plasmonic modes generated on its SiO2 interface, which explains the small outer metal layer influence on the observed modal dispersion.

Keywords

optics, photonics, plasmonics, SNOM tip, multimode optical fibre, spectral modulation, numerical simulation.

References

   1.  Hecht , B. , Sick , B. , Wild , U. P. , Deckert , V. , Zenobi , R. , Martin , O. J. F. , and Pohl , D. W. Scanning near-field optical microscopy with aperture probes: Fundamentals and applications. J. Chem. Phys. , 2000 , 112 , 7761–7774.
https://doi.org/10.1063/1.481382

   2.  Rähn , M. , Pärs , M. , Palm , V. , Jaaniso , R. , and Hizhnyakov , V. Mesoscopic effect of spectral modulation for the light transmitted by a SNOM tip. Opt. Commun. , 2010 , 283 , 2457–2460.
https://doi.org/10.1016/j.optcom.2010.02.010

   3.  Novotny , L. and Hafner , C. Light propagation in a cylindrical waveguide with a complex , metallic , dielectric function. Phys. Rev. E. , 1994 , 50 , 4094–4106.
https://doi.org/10.1103/PhysRevE.50.4094

   4.  Palm , V. , Rähn , M. , and Hizhnyakov , V. Modal dispersion due to photon-plasmon coupling in a SNOM tip. Opt. Commun. , 2012 , 285 , 4579–4582.
https://doi.org/10.1016/j.optcom.2012.07.008

   5.  Palm , V. , Rähn , M. , Jäme , J. , and Hizhnyakov , V. Excitation of surface plasmons in Al-coated SNOM tips. Proc. SPIE , 2012 , 84572S , 1–10.
https://doi.org/10.1117/12.929719

   6.  Palm , V. , Pärs , M. , Loot , A. , Rähn , M. , and Hizhnyakov , V. 2017. On mesoscopic effect of spectral modulation and its potential influence on hyperspectral SNOM imaging results. In Microscopy and imaging science: practical approaches to applied research and education (Méndez-Vilas , A. , ed.). Formatex Research Center , 610–619 , Badajoz , Spain.

   7.  Malitson , I. H. Interspecimen comparison of the refractive index of fused silica. J. Opt. Soc. Am. , 1965 , 55 , 1205–1209.
https://doi.org/10.1364/JOSA.55.001205

   8.  Rakic , A. D. , Djurisic , A. B. , Elazar , J. M. , and Majewski , M. L. Optical properties of metallic films for vertical-cavity optoelectronic devices. Appl. Opt. , 1998 , 37 , 5271–5283.
https://doi.org/10.1364/AO.37.005271

   9.  Johnson , P. B. and Christy , R. W. Optical constants of the noble metals. Phys. Rev. B , 1972 , 6 , 4370–4379.
https://doi.org/10.1103/PhysRevB.6.4370

10.  Marcuse , D. Light Transmission Optics. Van Nostrand Reinhold , New York , 1982.

11.  Delves , L. M. and Lyness , J. N. A numerical method for locating the zeros of an analytic function. Math. Comp. , 1967 , 21 , 543–560.
https://doi.org/10.1090/S0025-5718-1967-0228165-4

12.  Novotny , L. and Hecht , B. Principles of Nano-Optics. Cambridge University Press , New York , 2006.
https://doi.org/10.1017/CBO9780511813535

 
Back

Current Issue: Vol. 67, Issue 4 in Press, 2018




Publishing schedule:
No. 1: 20 March
No. 2: 20 June
No. 3: 20 September
No. 4: 20 December