Selective electro-magnetic absorbers based on metal-dielectric-metal thin-film cavities

142 Pages·2015·7.63 MB·English

SELECTIVEELECTRO-MAGNETICABSORBERSBASEDON
METAL-DIELECTRIC-METALTHIN-FILMCAVITIES
by
JANARDANNATH
M.S.UniversityofCentralFlorida,2011
Adissertationsubmittedinpartialfulfilmentoftherequirements
forthedegreeofDoctorofPhilosophy
intheDepartmentofPhysics
intheCollegeofSciences
attheUniversityofCentralFlorida
Orlando,Florida
SummerTerm
2015
MajorProfessor:RobertE.Peale
(cid:13)c 2015JanardanNath
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ABSTRACT
Efficientabsorptionoflightisrequiredforalargenumberofapplicationssuchasthermo-photovoltaics,
thermalimaging,bio-sensing,thermalemitters,astronomy,andstealthtechnology. Stronglightab-
sorbers found in nature with high intrinsic losses such as carbon black, metal-black, and carbon
nano-tubesetc. arebulky,notdesign-tunableandarehardtopatternformicro-andnano-devices.
We developed thin-film, high performance absorbers in the visible, near-, mid-, long-wave - and
far-IRregionbasedona3layermetal-dielectric-metal(MDM)structure.
Wefabricateda3-layerMDMabsorberwithlargeband-widthsinthevisibleandnearIR
spectral range without any lithographic patterning. This was the first demonstration in the optical
range of the Salisbury Screen, which was originally invented for radar absorption. A Fabry-Perot
cavity model depending on the thickness of the dielectric, but also the effective permittivity of the
semi-transparenttopmetalgivescalculatedspectrathatagreewellwithexperiment.
Secondly, we fabricated long-wave IR and far-IR MDM absorbers comprising surface
patternsofperiodicmetalsquaresonthedielectriclayer. Strongabsorptioninmultiplebandswere
obtained, and these depended weakly on polarization and angle of incidence. Though such ab-
sorbers had been extensively studied by electrodynamic simulations and experiment in the visible
to far- R regions, there existed no analytic model that could accurately predict the wavelengths of
the multiple resonances. We developed a theoretical model for these absorbers based on standing-
waveresonances,whichaccuratelypredictsresonancewavelengthsforexperimentandsimulation
for the first time. Unlike metamaterial theories our model does not depend on the periodicity of
the squares but only on their lateral dimension and the thickness of the dielectric. This feature is
confirmedbysynchrotron-basedIRspectralimagingmicroscopyofsingleisolatedsquares.
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Idedicatethisworktomyparents,mysisters,mynephewandmywife.
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ACKNOWLEDGMENTS
First of all I acknowledge my supervisor Prof. Robert Peale for accepting me in his group and
supporting me through out my PhD. He has given me a lot of freedom with my research. He
believedinmyideasandguidedmewithvaluablesuggestions. Heworkedhardinfundingmeand
my lab mates. He has maintained a wonderful environment in the lab by being kind and patient. I
thankProf. RobertPealeforhiswonderfuladvisinginmyPhD.
I would like to thank my committee Dr. Masahiro Ishigami, Prof. Leonid Chernyak,
andProf. KonstantinL.Vodopyanovforacceptingtohelpandguidemeformydissertation.
I acknowledge my lab-mates for their support, love and inspiration. Especially, I thank
Mr. Farnood Rezaie, Dr. Deep Panjwani, Dr. Monas Shahzad, Mr. Pedro Figueiredo, Dr. Gau-
tam Medhi, Mr. Imen Razadad, Ms. Javaneh Boroumand, Mr. Evan Smith, and Dr. Tatyana
Brusentsova for their help with various projects. I thank Mr. Sushrut Modak for always help-
ing me with FDTD simulations. I thank Dr. Ryuichi Tsuchikawa for assistance with the AFM
measurements. I am very grateful to Mr. Douglas Maukonen for his help with the spectroscopic
measurements. I thank Dr. Walter R Buchwald, Dr. Justin Cleary, Dr. Nima Nader, Dr. Josh
HendricksonandDr. KurtG.EyinkofAirForceResearchLaboratory,Daytonforhelpinguswith
various experiments. I would like to thank Prof. Leonid Chernyak, Dr. Elena Flitsiyan and Dr.
CaseySchwarzforthehelpwiththecathodoluminescenceexperiments.
I thank Dr. Mehmet Yeslitas for the measurements with synchrotron microscopy. I
thank Mr. Chris Fedrickson, Dr. Isaiah Oladeji, Dr. A. V. Muravjov and Mr. Guy Zummo for
the help and guidance with different instruments. I would also like to thank Physics department
facultymembersandofficestaff,whohelpedmethroughoutmyacademicprogram.
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I would like to thank Dr. J. David Musgraves, Mr. Pete Wachtel, and Ms. Jennifer
McKinley of IRradiance Glass Inc., for the help with IR glass projects. Especially, I would like to
thank Pete for his guidance with the glass melting and asking valuable questions in my research
projects.
I would like to thank my wife Vaahini Ganesan for her moral support and standing by
methroughupsanddownsduringmyPhD.IthankallmyfriendsandUCFcommunitywhomade
mylifeanenjoyableexperienceforthelast6years.
Iwouldliketothankmyparentsandmysistersfortheirinvaluablesupport.
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TABLE OF CONTENTS
LISTOFFIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xviii
CHAPTER1: INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 PlasmonicAbsorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Fabry-PerotTypeAbsorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 MetamaterialAbsorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
CHAPTER2: THEORETICALBACKGROUND . . . . . . . . . . . . . . . . . . . . . . 10
2.1 EffectiveMediumTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.1 2-PhaseMedia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2 Maxwell-GarnetTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.3 BruggemanTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 MetamaterialAbsorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2.1 MagneticResonanceTheory . . . . . . . . . . . . . . . . . . . . . . . . . 15
vii
2.2.2 InterferenceTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2.3 PlanarWave-guideTheory . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2.4 Metal-dielectric-metal(MDM)CavityTheory . . . . . . . . . . . . . . . . 18
2.3 FiniteDifferenceTimeDomain(FDTD)Method . . . . . . . . . . . . . . . . . . 19
2.3.1 FiniteDifferenceMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3.2 DerivationofFDTDEquations . . . . . . . . . . . . . . . . . . . . . . . . 20
CHAPTER3: FAR INFRA-RED ABSORBER BASED ON STANDING-WAVE RESO-
NANCESINMETAL-DIELECTRIC-METALCAVITY . . . . . . . . . . . 22
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3 ExperimentalDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.4.1 FDTDSimulationResults . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
CHAPTER4: OPTICALSALISBURYSCREENWITHDESIGN-TUNABLERESONANT
ABSORPTIONBANDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
viii
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.2 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.3 ExperimentalDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.4 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.4.1 MetalNano-discs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
CHAPTER5: WIDE-BAND LONG-WAVE INFRA-RED (LWIR) METAL-DIELCTRIC-
METALTHINFILMABSORBER . . . . . . . . . . . . . . . . . . . . . . 78
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.2 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3 FDTDSimulationResults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.4 ExperimentalDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.5 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
CHAPTER6: SYNCHROTRON INFRA-RED SPECTRAL MICROSCOPY OF METAL-
DIELECTRIC-METALCAVITYMETAMATERIALABSORBERS . . . . . 96
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
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6.2 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.3 ExperimentalDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.4 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
CHAPTER7: CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
LISTOFREFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
x