Supplemental Document

Hybrid metasurfaces for simultaneous focusingand filtering: supplement

MANSOOR A. SULTAN,1 FATIH BALLI,2 DANIEL L. LAU,1 ANDJ. TODD HASTINGS1,∗

1Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky 40506,USA2Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA∗Corresponding author: todd.hastings@uky.edu

This supplement published with The Optical Society on 4 January 2021 by The Authors underthe terms of the Creative Commons Attribution 4.0 License in the format provided by the authorsand unedited. Further distribution of this work must maintain attribution to the author(s) and thepublished article’s title, journal citation, and DOI.

Supplement DOI: https://doi.org/10.6084/m9.figshare.13348271

Parent Article DOI: https://doi.org/10.1364/OL.410080

Hybrid Metasurfaces forSimultaneous Focusing and Filtering -Supplemental DocumentMANSOOR A. SULTAN1, FATIH BALLI2, DANIEL L. LAU1,AND J. TODD HASTINGS1,*

1Department of Electrical and Computer Engineering, University of Kentucky, Lexington, Kentucky40506, USA2Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA*Corresponding author: todd.hastings@uky.edu

1. EXPERIMENTAL SETUP

The optical setup for filter characterization is shown in Fig. S1. The light source is halogen-deuterium fiber coupled source from Ocean Optics. Two types of camera were used: a colorcamera (Amscope MU100) and gray-scale camera (Ximea-xiQ). The spectrophotometer is aUV-NIR model (HR4000CG-UV-NIR) from Ocean Optics.

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Fig. S1. Experimental setup for filter characterization

2. FABRICATION PROCESS

The filters were fabricated on fused silica substrates of 0.7mm thickness with IP-DIP resist(Nanoscribe GmbH). After exposure the sample was developed for 20 min with 2-Methoxy-1-methylethyl acetate (PGMEA from J.T. Baker) then rinsed for 3 min in IPA and 30 seconds in 3MNovec 7100 Engineered Fluid (2-(Difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoro-propane).

3. SUPPLEMENTARY SIMULATIONS

A. Higher diffracted ordersAs noted in the main text, the diffracted light from the filter is removed by angular or spatialfiltering. Figure S2 shows the simulated far-field projections of a green filter alongside the NA ofthe objective. In all cases the higher diffracted orders fall outside the NA of the objective.

B. Filter simulationsThe simulation model of the focusing filters was based on single pixel filter with perfectly matchedlayers (PML) on all boundaries (x = y = −25µm : +25µm, z = −4µm : +55µm) and total scatteringfield source (TSFS). The lower boundary of the source was placed 2µm below the filter pixelinside the substrate. A frequency domain power monitor was placed in the focal plane of thefilter. The focusing efficiency was calculated by integrating the Poynting vector over a circulararea of 5µm radius and dividing by the source power. The area was chosen with this size to matchthe experiments. Figures (S3 & S4 ) show the incident angle effect on the optical power profileand focusing efficiency.

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Fig. S2. Far-field profiles (log scale) for the green filter normalized to the minimum field at450nm wavelength. The wavelengths are (a) 450 nm, (b) 550 nm, and (c) 650 nm. The accep-tance angle of the objective is shown in orange, and all diffracted orders but zero fall beyondthe objective’s NA.

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Fig. S3. Optical power profile of a green filter in the xz-plane at different angles of incidenceand different wavelengths as labeled on the figure. A change in the angle of incidence movesthe focused spot as expected, and reduces the overall transmission, but has little effect on therelative transmitted power among the three wavelengths.

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4. SPECTRAL RESPONSE OF THE PHASE PLATE ALONE

In addition to the complete filter fabrication (phase plate + pillars), We fabricated the phase-plateonly and measured the focusing efficiency to study the effect of phase-plate on the filteringprocess. The results are shown in Fig. S5.

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Fig. S5. Focusing efficiency of phase-plate layer without pillars on top for the three main filters.The phase plate has a relatively weak effect on the green and red filters, but influences the bluefilter significantly.

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