View source for Extraordinary optical transmission

[[Image:Subwavelength slits.JPG|thumb|right|Interference pattern of double slits, where the slit width is one third the wavelength.]]

'''Extraordinary optical transmission''' ('''EOT''') is the phenomenon of greatly enhanced transmission of light through a [[subwavelength]] aperture in an otherwise opaque metallic film which has been patterned with a regularly repeating periodic structure.  Generally when [[light]] of a certain [[wavelength]] falls on a subwavelength aperture, it is [[diffraction|diffracted]] [[Isotropy|isotropically]] in all directions evenly, with minimal [[far-field]] transmission.  This is the understanding from classical aperture theory as described by [[Hans Bethe|Bethe]].<ref>{{Cite journal | last1 = Bethe | first1 = H. | title = Theory of Diffraction by Small Holes | doi = 10.1103/PhysRev.66.163 | journal = Physical Review | volume = 66 | issue = 7–8 | pages = 163–182| year = 1944 |bibcode = 1944PhRv...66..163B }}</ref>  In EOT however, the regularly repeating structure enables much higher transmission efficiency to occur, up to several orders of magnitude greater than that predicted by classical aperture theory. It was first described in 1998.<ref>{{cite journal|author1=T. W. Ebbesen |author2=H. J. Lezec |author3=H. F. Ghaemi |author4=T. Thio |author5=P. A. Wolff |title=Extraordinary optical transmission through sub-wavelength hole arrays |journal=Nature |volume=391 |issue=6668 |pages=667–669 |year=1998 |doi=10.1038/35570 |url=http://arep.med.harvard.edu/pdf/Ebbsen98.pdf|bibcode = 1998Natur.391..667E |s2cid=205024396 }}</ref><ref>{{cite journal|author1=Ebbesen, T. W. |author2=Ghaemi, H. F. |author3=Thio, Tineke |author4=Grupp, D. E. |author5=Lezec, H. J |title=Extraordinary Optical Transmission through Sub-wavelength Hole Arrays|journal=Abstract from a Talk at the 1998 American Physical Society's Annual March Meeting|page=S15.11|date=March 1998|bibcode=1998APS..MAR.S1511E}}</ref>

This phenomenon that was fully analyzed with a microscopic scattering model is ''partly'' attributed to the presence of [[surface plasmon]] resonances<ref>{{cite journal|author1=H. Liu |author2=P. Lalanne |title=Microscopic theory of the extraordinary optical transmission |journal=Nature|volume=452|issue=7188 |pages=728–731|year=2008|doi=10.1038/nature06762 |pmid=18401405 |bibcode=2008Natur.452..728L |s2cid=4400944 }}</ref> and [[constructive interference]]. A surface plasmon (SP) is a collective excitation of the [[electron]]s at the junction between a [[Electrical conductor|conductor]] and an [[Electrical insulation|insulator]] and is one of a series of interactions between light and a metal surface called [[Plasmonics]].

Currently, there is experimental evidence of EOT out of the optical range.<ref>{{cite journal|author1=M. Beruete |author2=M. Sorolla |author3=I. Campillo |author4=J.S. Dolado |author5=L. Martín-Moreno |author6=J. Bravo-Abad |author7=F. J. García-Vidal |title=Enhanced Millimeter Wave Transmission Through Quasioptical Subwavelength Perforated Plates|journal=IEEE Transactions on Antennas and Propagation|volume=53|issue=6|pages=1897–1903|year=2005|doi=10.1109/TAP.2005.848689|bibcode = 2005ITAP...53.1897B |s2cid=7510282 }}</ref> Analytical approaches also predict EOT on perforated plates with a [[perfect conductor]] model.<ref>{{cite journal|author=C.C. Chen|title=Transmission through a Conducting Screen Perforated Periodically with Apertures|journal=IEEE Trans. Microw. Theory Tech.|volume=18|issue=9|pages=627–632|year=1970|doi=10.1109/TMTT.1970.1127298|bibcode = 1970ITMTT..18..627C }}</ref><ref>{{cite journal|author1=L. Martín-Moreno |author2=F. J. García-Vidal |author3=H. J. Lezec |author4=K. M. Pellerin |author5=T. Thio |author6=J. B. Pendry |author7=T.W. Ebbesen |title=Theory of Extraordinary Optical Transmission through Subwavelength Hole Arrays|journal=Phys. Rev. Lett.|volume=86|pages=1114–1117|year=2001|doi=10.1103/PhysRevLett.86.1114|pmid=11178023|issue=6|bibcode=2001PhRvL..86.1114M|arxiv = cond-mat/0008204 |s2cid=17392720 }}</ref><ref>{{cite journal|author=F. J. Garcia de Abajo, R. Gomez-Medina, and J. J. Saenz|title=Full transmission through perfect-conductor subwavelength hole arrays|journal=Phys. Rev. E|volume=72|page=016608|year=2005|pmid=16090108|doi=10.1103/PhysRevE.72.016608|arxiv = 0708.0991 |bibcode = 2005PhRvE..72a6608G|issue=1 Pt 2|s2cid=31746296}}</ref> Holes can somewhat emulate [[plasmons]] at other regions of the [[electromagnetic spectrum]] where they do not exist.<ref>{{cite journal|author1=R. Ulrich |author2=M. Tacke |title=Submillimeter waveguiding on periodic metal structure|journal=Appl. Phys. Lett.|volume=22|issue= 5|pages=251–253|year=1972|doi= 10.1063/1.1654628|bibcode = 1973ApPhL..22..251U }}</ref><ref>{{cite journal|author1=J. B. Pendry |author2=L. Martín-Moreno |author3=F. J. García-Vidal |title=Mimicking surface plasmons with structured surfaces|journal=Science|volume=305|pages=847–848|year=2004|doi=10.1126/science.1098999|pmid=15247438|issue=5685|bibcode = 2004Sci...305..847P |s2cid=44412157 |doi-access=free}}</ref><ref>{{cite journal|author=F. J. Garcia de Abajo and J. J. Saenz|title=Electromagnetic surface modes in structured perfect-conductor surfaces|journal=Phys. Rev. Lett.|volume=95|issue=23|page=233901|year=2005|pmid=16384307|doi=10.1103/PhysRevLett.95.233901|arxiv = cond-mat/0506087 |bibcode = 2005PhRvL..95w3901G |s2cid=35201303}}</ref> Then, the plasmonic contribution is a very particular peculiarity of the EOT resonance and should not be taken as the main contribution to the phenomenon. More recent work has shown a strong contribution from overlapping [[evanescent wave coupling]],<ref>{{cite journal|author1=Z. Y. Fan |author2=L. Zhan |author3=X. Hu |author4=Y. X. Xia |title=Critical process of extraordinary optical transmission through periodic subwavelength hole array: Hole-assisted evanescent-field coupling|journal=Optics Communications|volume=281|issue=21|pages=5467–5471|year=2008|doi=10.1016/j.optcom.2008.07.077|bibcode = 2008OptCo.281.5467F }}</ref> which explains why [[surface plasmon resonance]] enhances the EOT effect on both sides of a metallic film at optical frequencies, but accounts for the terahertz-range transmission.

Simple analytical explanations of this phenomenon have been elaborated, emphasizing the similarity between arrays of particles and arrays of holes, and establishing that the phenomenon is dominated by [[diffraction]].<ref>{{cite journal|author=F. J. García de Abajo|title=Light scattering by particle and hole arrays|journal=Reviews of Modern Physics|volume=79|issue=4|pages=1267–1290|year=2007|doi=10.1103/RevModPhys.79.1267|bibcode=2007RvMP...79.1267G|arxiv = 0903.1671 |s2cid=18698507}}</ref><ref>{{cite journal|author1=B. Ung |author2=Y. Sheng |title=Optical surface waves over metallo-dielectric nanostructures: Sommerfeld integrals revisited|journal=Optics Express|volume=16|pages=9073–9086|year=2008|doi=10.1364/OE.16.009073|pmid=18545619|issue=12|arxiv = 0803.1696 |bibcode = 2008OExpr..16.9073U |s2cid=31651739 }}</ref><ref>{{cite journal|author1=M. W. Maqsood |author2=R. Mehfuz |author3=K. J. Chau |title=High-throughput diffraction-assisted surface-plasmon-polariton coupling by a super-wavelength slit|journal=Optics Express|volume=18|issue=21|pages=21669–21677|year=2010|doi=10.1364/OE.19.010429|pmid=21643298 |bibcode = 2011OExpr..1910429C |hdl=10261/47346 |hdl-access=free}}</ref>

==Applications==
EOT is expected to play an important role in the creation of components of efficient photonic integrated circuits (PICs). Photonic integrated circuits are analogous to electronic circuits but based upon photons instead of electrons.

One of the most ground-breaking results linked to EOT is the possibility to implement a Left-Handed [[Metamaterial]] (LHM) by simply stacking hole arrays.<ref>{{cite journal|author1=M. Beruete |author2=M. Sorolla |author3=I. Campillo |title=Left-Handed Extraordinary Optical Transmission through a Photonic Crystal of Subwavelength Hole Arrays|journal=Optics Express|volume=14|issue=12|pages=5445–5455|year=2006|doi=10.1364/OE.14.005445|pmid=19516710|bibcode = 2006OExpr..14.5445B |hdl=2454/31091 |hdl-access=free}}</ref>

EOT-based chemical and biological sensing (for example, improving ELISA based antibody detection) is another major area of research.<ref>{{cite journal|author1=A. De Leebeeck |author2=L. K. S. Kumar |author3=V. de Lange |author4=D. Sinton |author5=R. Gordon |author6=A. G. Brolo |title=On-chip surface-based detection with nanohole arrays|journal=Anal Chem|volume=79|pages=4094–4100|year=2007|doi= 10.1021/ac070001a|pmid= 17447728|issue= 11}}</ref><ref>{{cite journal|author1=A. G. Brolo |author2=R. Gordon |author3=K. L. Kavanagh |title= A new generation of sensors based on extraordinary light transmission|journal=Acc. Chem. Res.|volume=41|pages= 1049–1057|year=2008|doi= 10.1021/ar800074d|pmid= 18605739|issue= 8}}</ref><ref>{{cite journal|author1=N. H. Mack |author2=J. W. Wackerly |author3=V. Malyarchuk |author4=J. A. Rogers |author5=J. S. Moore |author6=R. G. Nuzzo |title=Optical transduction of chemical forces|journal=Nano Lett|volume=7|pages=733–737|year=2007|doi= 10.1021/nl0629759|pmid= 17309317|issue= 3|bibcode = 2007NanoL...7..733M }}</ref><ref>{{cite journal|author1=J. M. Yao |author2=M. E. Stewart |author3=J. Maria |author4=T. W. Lee |author5=S. K. Gray |author6=J. A. Rogers |author7=R. G. Nuzzo |title=Seeing molecules by eye: Surface plasmon resonance imaging at visible wavelengths with high spatial resolution and submonolayer sensitivity|journal=Angewandte Chemie International Edition|volume=47|pages=5013–5017|year=2008|doi= 10.1002/anie.200800501|pmid= 18512212|issue= 27}}</ref><ref>{{cite journal|author1=P. R. H. Stark |author2=A. E. Halleck |author3=D. N. Larson |title=Short order nanohole arrays in metals for highly sensitive probing of local indices of refraction as the basis for a highly multiplexed biosensor technology|journal=Methods|volume=37|pages=37–47|year=2005|doi= 10.1016/j.ymeth.2005.05.006|pmid= 16199175|issue= 1}}</ref><ref>{{cite journal|author1=J. C. Yang |author2=J. Ji |author3=J. M. Hogle |author4=D. N. Larson |title=Multiplexed plasmonic sensing based on small-dimension nanohole arrays and intensity interrogation|journal=Biosens Bioelectron |year=2009|doi= 10.1016/j.bios.2008.12.011|volume= 24|pages= 2334–8|pmid= 19157848|issue= 8|pmc= 2716172}}</ref><ref>{{cite journal|author1=J. Ji |author2=J. G. O'Connell |author3=D. J. D. Carter |author4=D. N. Larson |title=High-throughput nanohole array based system to monitor multiple binding events in real time|journal=Anal Chem |pages=2491–2498|year=2008|doi= 10.1021/ac7023206|volume= 80|pmid= 18307360|issue= 7}}</ref><ref>{{cite journal|author1=J. C. Yang |author2=J. Ji |author3=J. M. Hogle |author4=D. N. Larson |title=Metallic nanohole arrays on fluoropolymer substrates as small label-free real-time bioorobes|journal=Nano Lett|volume=8|pages=2718–2724|year=2008|doi= 10.1021/nl801043t|pmid= 18710296|issue= 9|pmc= 2662724|bibcode = 2008NanoL...8.2718Y }}</ref> Much like in a traditional [[surface plasmon resonance]] sensor, the EOT efficiency varies with the wavelength of the incident light, and the value of the in-plane wavevector component. This can be exploited as a means of transducing chemical binding events by measuring a change in the local [[dielectric constant]] (due to binding of the target species) as a shift in the spectral location and/or intensity of the EOT peak. Variation of the hole geometry alters the spectral location of the EOT peak such that the chemical binding events can be optically detected at a desired wavelength.<ref>{{cite journal|author1=Mehdi Tavakoli |author2=Yousef Seyed Jalili |author3=Seyed Mohammad Elahi |title=Rayleigh-Wood anomaly approximation with FDTD simulation of plasmonic gold nanohole array for determination of optimum extraordinary optical transmission characteristics|journal=Superlattices and Microstructures |year=2019|doi= 10.1016/j.spmi.2019.04.035|volume= 130|pages= 454–471|bibcode=2019SuMi..130..454T |s2cid=150365680 }}</ref> EOT-based sensing offers one key advantage over a Kretschmann-style SPR chemical sensor, that of being an inherently nanometer-micrometer scale device; it is therefore particularly amenable to miniaturization.<ref>{{cite journal |last1=Lameirinhas |first1=Ricardo A. Marques |last2=N. Torres |first2=Joao Paulo |last3=Baptista |first3=António |last4=M. Martins |first4=Maria Joao |title=A Novel Analysis for Light Patterns in Nano Structures |journal=IEEE Photonics Journal  |year=2022|doi=10.1109/JPHOT.2022.3227429|doi-access=free }}</ref>

==References==
{{reflist|2}}

[[Category:Quantum optics]]
[[Category:Electromagnetism]]
[[Category:Plasmonics]]
[[Category:Metamaterials]]