Supporting Information Quantitative 3D phase imaging of plasmonic metasurfaces

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Ann Bryant
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1 Supporting Information Quantitative 3D phase imaging of plasmonic metasurfaces Jiří Babocký 1,2, Aneta Křížová 1,2, Lenka Štrbková 1, Lukáš Kejík 1, Filip Ligmajer 1,3, Martin Hrtoň 1,3, Petr Dvořák 1,3, Matěj Týč 1, Jana Čolláková 1,3, Vlastimil Křápek 1,3, Radek Kalousek 1,3, Radim Chmelík 1,3, and Tomáš Šikola 1,3,*. 1 Central European Institute of Technology, Purkyňova 123, Brno, , Czech Republic 2 TESCAN Brno, s.r.o., Libušina tř. 1, Brno, Czech Republic 3 Institute of Physical Engineering, Brno University of Technology, Technická 2896/2, Brno, , Czech Republic * Address correspondence to: sikola@fme.vutbr.cz (T. Š.)

2 1. Fabrication of nanodiscs Figure S1: SEM images of fabricated nanodiscs. Yellow labels indicate the designed nanodisc diameter, the scale bar is 400 nm. The vacancies in the arrays of 50 nm and 60 nm nanodiscs are due to limited resolution of PMMA resist and lift-off process.

3 Figure S2: Real dimensions of fabricated nanodiscs (obtained from SEM images) compared to the designed nanodiscs: Blue and green points show the diameter of maximal and minimal discs inscribed into the fabricated nanoantennas, red points show the mean diameter of the fabricated nanoantennas.

4 2. FDTD simulations Figure S3: Calculated extinction (left) and phase (right) spectra for several disc diameters. Solid lines correspond to perfect discs, while the dashed and dotted lines belong to discs which are elongated in the direction parallel to the incident polarization and equally narrowed in the perpendicular one. The elongation parameter (half the long axis minus the original disc radius) is 5 nm for the dashed lines and 10 nm for the dotted ones. For comparison, the values extracted from SEM images (see Figure S2) are between 5 and 10 nm. Figure S4: Calculated extinction (left) and phase (right) spectra for several disc diameters and three thicknesses of silver oxide layer. Solid lines belong to discs without oxide. In the case of dashed lines, the outermost 2.5 nm of the disc (except the bottom side adjacent to the substrate) was replaced by a silver oxide (its dielectric function was approximated by a constant value 2.5). 1 For the dotted lines, the thickness of silver oxide was 5 nm.

5 3. Speckles in CCHM images Figure S5: Detailed CCHM phase image or plasmonic nanoantenna array (disc diameter 180 nm, illumination wavelength 700 nm) with an overlay showing the actual array design. It is obvious that the periodicity of observed speckles (about 1.4 µm) is far larger than the nanoantenna pitch (360 nm). The scale bar is 2 µm.

6 4. Calculated field distributions behind ideal and realistic zone plates Figure S6: (a) Distribution of the electric field in the image plane of the microscope along a line running from the center of the zone plate to its edge. The solid blue and green lines depict the real and imaginary part of the electric field which was calculated by inserting the real distribution of silver nanodiscs into our theoretical model. The solid red and purple lines indicate an ideal field distribution with zone boundaries taken from the analytical model that was used for the design of the zone plate. The field distribution represented by the dotted red and purple lines was obtained by deforming the ideal distribution so it captures more accurately the full profile. It illustrates the fact that between neighboring zones the field changes gradually and the zones are therefore effectively narrower than in the design. (b) Phase map calculated from the electric field distribution with ideal zone dimensions. (c) Phase map calculated from the electric field distribution with narrower zones. Although the main focal point at z 100 µm remains unaffected, the use of the more realistic field distribution with narrower zones leads to a shift in the position of the secondary focal point (from z 33 µm to z 50 µm), an effect observed both in the experiment and the calculations with the full field distribution (shown in Figure 5c,d). (1) Qiu, J.-H.; Zhou, P.; Gao, X.-Y.; Yu, J.-N.; Wang, S.-Y.; Li, J.; Zheng, Y.-X.; Yang, Y.-M.; Song, Q.- H.; Chen, L.-Y. Ellipsometric Study of the Optical Properties of Silver Oxide Prepared by Reactive Magnetron Sputtering. J. Korean Phys. Soc 2005, 46, S269--S275.

Supplementary Information

Electronic Supplementary Material (ESI) for Nanoscale. This journal is The Royal Society of Chemistry 2014 Supplementary Information Large-scale lithography-free metasurface with spectrally tunable super