See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/325330206 Experimental demonstration of soliton-plasmon coupling in planar waveguides (Conference Presentation) Conference Paper · May 2018 DOI: 10.1117/12.2305939 CITATIONS READS 0 82 7 authors , including: Tintu Kuriakose Tomá š Halenkovi č The University of Sheffield University of Pardubice 12 PUBLICATIONS 78 CITATIONS 16 PUBLICATIONS 110 CITATIONS SEE PROFILE SEE PROFILE Mahmoud M. R. Elsawy Petr Nemec National Institute for Research in Computer Science and Control University of Pardubice 20 PUBLICATIONS 54 CITATIONS 169 PUBLICATIONS 2,084 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Soliton channel for télécoms View project Glass exploration View project All content following this page was uploaded by Mathieu Chauvet on 02 June 2018. The user has requested enhancement of the downloaded file.
Experimental demonstration of soliton-plasmon coupling in planar waveguides Tintu Kuriakose, Mathieu Chauvet FEMTO-ST Institute, UMR CNRS 6174, Université de Franche-Comté, 15B avenue des Montboucons, 25030 Besançon – France Gilles Renversez, Mahmoud M. R. Elsawy Université d´Aix-Marseille, CNRS, Centrale Marseille, Institut Fresnel, Marseille 13013, France Virginie Nazabal Institut des sciences chimiques de Rennes, UMR CNRS 6226, Equipe Verres et Céramiques, Université de Rennes 1, 35042 Rennes, France Tomas Halenkovic, Petr Němec Department of Graphic Arts and Photophysics, Faculty of chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice, Czech Republic tintu.kuriakose@femto-st.fr Merging the fields of plasmonics and nonlinear optics authorizes a variety of fascinating and original physical phenomena. In this study, we specifically study the combination of the strong light confinement ability of surface plasmon polaritons (SPP) with the beam self-trapping effect that occur in nonlinear optical Kerr medium. Although this idea of plasmon-soliton has been the subject of several theoretical papers [1-4], no experimental evidence have yet been revealed. One reason is that in the proposed configurations the requested nonlinear refractive index change amplitude to generate a plasmon-soliton is too high to be reached in available material. Another limitation is due to the large propagation losses associated with plasmons. In the present study, a proper architecture has been studied and fabricated allowing the first experimental observation of hybrid coupling between a spatial soliton and SPP in a metal-Kerr dielectric structure. To be able to trigger the nonlinearity at moderate light power and simultaneously allow propagation over several millimeters distance, a metal-dielectric structure was designed [5]. It consists of a four–layer planar geometry made of a transparent Kerr dielectric layer placed on a lower refractive index medium with a thin dielectric layer followed by a metallic film deposited on top. The Kerr medium is a 3µm thick chalcogenide film (Ge 28.1 Sb 6.3 Se 65.6) with a high refractive index deposited by RF magnetron sputtering on an oxidized silicon substrate. Note that this waveguide structure was previously used to demonstrate the formation of spatial solitons [6] thanks to the large third order nonlinearity of the chalcogenide glass. To exploit the plasmonic effect, part of the structure is covered with a thin 10nm SiO 2 layer and a 30nm thick gold layer. Samples are about 5-6 mm along propagation direction. Performed numerical simulations show that the designed planar structure supports a fundamental TE mode profile at NIR wavelengths whose transverse profile along y (perpendicular to the layers) is not affected by the metal layer while the TM mode is clearly confined at the SiO 2 -metal-chalcogenide interfaces due to the plasmonic effect. In nonlinear regime an enhanced self-focusing effect is thus expected for this TM wave since its intensity distribution is higher compare to the TE polarized one. Experiments are performed with a tunable optical parametric oscillator emitting 200 fs pulses at a repetition rate of 80 MHz. The experimental analysis consist in injecting a typical 4 × 30 μm 2 (FWHM) elliptical laser beam into the waveguide and monitoring the output beam profile evolution versus light power. Different arrangements are tested that unambiguously reveal the plasmon-soliton coupling. For instance, experiments are
conducted with and without the metallic layer and for both TE and TM polarizations. In addition, several positions of the metallized part on the sample are tested along with varying length chosen between 0.1 to 2mm. Figure 1 presents the self-focusing behavior of light as a function of intensity observed in a 5.5 mm long sample without electrode for TM and with metallic layer for both TE and TM polarizations at a 1550nm wavelength. The behavior of a TE wave without metal is not shown since it is identical than the TE case. The metallic layer is 0.66 mm long and is positioned near the exit face of the sample. The input beam size is 4 × 33 μm 2 (FWHM) in the guided ( � ) and transverse dimension ( � ), respectively. At low power, the beam diffracts to about 40 µm at the exit face independently of polarizations or waveguide structure (Fig.1 a, d, g). At high input intensity (0.75 GW/cm²), we observed a beam narrowing (Fig. 1 b, e, h) which is clearly stronger for the TM polarization in presence of the electrode (Fig. 1 e). Further increase of intensity (1.2 GW/cm²) leads to a very efficient trapping of beam as witnessed by the beam size reduction to 11 µm (Fig. 1 f). This hybrid plasmonic geometry is thus definitely providing an enhanced self-focusing nonlinearity. The strong confinement of light observed in our structure confirms the coupling between the plasmon and the soliton waves. Additional experiments are in progress to analyze the beam evolution with near-field scanning microscopy and numerical simulations are developed to better comprehend the observed powerful self-trapping. Figure.1: Comparison of self-focusing behavior of light as a function of intensity without metal (I. a-c) and hybrid plasmon-soliton waveguide under TM polarization (II. d-f) and for TE polarization (II. g-I). Metallic layer is 0.66 mm long and it is positioned near the exit face of the sample. References [1] E. Feigenbaum et M. Orenstein, « Plasmon-soliton », Opt. Lett. , vol. 32, n o 6, p. 674–676, 2007. [2] A. R. Davoyan, I. V. Shadrivov, et Y. S. Kivshar, « Self-focusing and spatial plasmon-polariton solitons », Opt. Express , vol. 17, n o 24, p. 21732–21737, 2009.
[3] J. Ariyasu, C. T. Seaton, G. I. Stegeman, A. A. Maradudin, et R. F. Wallis, « Nonlinear surface polaritons guided by metal films », J. Appl. Phys. , vol. 58, n o 7, p. 2460‑2466, oct. 1985. [4] P. Ginzburg, A. V. Krasavin, et A. V. Zayats, « Cascaded second-order surface plasmon solitons due to intrinsic metal nonlinearity », New J. Phys. , vol. 15, n o 1, p. 013031, janv. 2013. [5] W. Walasik, V. Nazabal, M. Chauvet, Y. Kartashov, et G. Renversez, « Low-power plasmon–soliton in realistic nonlinear planar structures », Opt. Lett. , vol. 37, n o 22, p. 4579–4581, 2012. [6] T. Kuriakose et al. , « Measurement of ultrafast optical Kerr effect of Ge–Sb–Se chalcogenide slab waveguides by the beam self-trapping technique », Opt. Commun. , vol. 403, p. 352‑357, nov. 2017. View publication stats View publication stats
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