Editing ARROW waveguide (section)

== Applications ==
ARROW are often used for guiding light in liquids, particularly in photonic [[lab-on-a-chip]] analytical systems (PhLoCs).<ref>{{Cite journal|last1=Kathleen|first1=Bates E.|last2=Lu|first2=Hang|title=Optics-Integrated Microfluidic Platforms for Biomolecular Analyses|url= |journal=Biophysical Journal|date=26 April 2016|volume= 110|issue= 8|pages=1684–1697|bibcode = 2016BpJ...110.1684B |doi = 10.1016/j.bpj.2016.03.018 |pmid=27119629|pmc=4850344}}</ref><ref>{{Cite journal|last1=Schmidt|first1=Holger|last2=Yin|first2=Dongliang|last3=Deamer|first3=David W.|last4=Barber|first4=John P.|last5=Hawkins|first5=Aaron R.|editor2-first=Louay A|editor2-last=Eldada|editor1-first=Elizabeth A|editor1-last=Dobisz|author5-link= Aaron Hawkins (engineer) |title=Integrated ARROW waveguides for gas/liquid sensing.|url=http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=849063|journal=Nanoengineering: Fabrication, Properties, Optics, and Devices|date=August 2, 2004|volume=5515|page=67|doi=10.1117/12.558946|bibcode=2004SPIE.5515...67S |s2cid=137407772}}</ref><ref>{{Cite journal|last1=Yin|first1=D.|last2=Schmidt|first2=H.|last3=Barber|first3=J.P.|last4=Hawkins|first4=A.R.|author4-link= Aaron Hawkins (engineer) |date=2004-06-14|title=Integrated ARROW waveguides with hollow cores|url=https://www.osapublishing.org/oe/abstract.cfm?uri=OE-12-12-2710|journal=Optics Express|language=EN|volume=12|issue=12|pages=2710–5|doi=10.1364/OPEX.12.002710|pmid=19475112|issn=1094-4087|bibcode = 2004OExpr..12.2710Y |doi-access=free}}</ref><ref>{{Cite journal|last1=Cai|first1=H.|last2=Parks|first2=J. W.|last3=Wall|first3=T. A.|last4=Stott|first4=M. A.|last5=Stambaugh|first5=A.|last6=Alfson|first6=K.|last7=Griffiths|first7=A.|last8=Mathies|first8=R. A.|last9=Carrion|first9=R.|date=2015-09-25|title=Optofluidic analysis system for amplification-free, direct detection of Ebola infection|journal=Scientific Reports|language=en|volume=5|pages=14494|doi=10.1038/srep14494|issn=2045-2322|bibcode = 2015NatSR...514494C |pmc=4585921|pmid=26404403}}</ref> Conventional waveguides rely on the principle of total internal reflection, which can only occur if the refractive index of the guiding core material is greater than the refractive indexes of its surroundings. However, the materials used to make the guiding core are typically polymer and silicon-based materials, which have higher refractive indexes (n=1.4-3.5) than that of water (n = 1.33). As a result, a conventional hollow-core waveguide no longer works once it's filled with water solution, making the PhLoCs useless. An ARROW, on the other hand, can be liquid-filled since it confines light completely by interference, which requires that the refractive index of the guiding core to be lower than the refractive index of the surrounding materials. Thus, ARROWs become the ideal building blocks for PhLoCs.

Though ARROWs carry big advantage over conventional waveguide for building PhLoCs, they are not perfect. The main problem of ARROW is its undesirable light loss. Light loss of ARROWs decreases the signal to noise ratio of the PhLoCs. Different versions of ARROWs have been designed and tested in order to overcome this problem.<ref>{{Cite journal|last1=Wall|first1=Thomas A.|last2=Chu|first2=Roger P.|last3=Parks|first3=Joshua W.|last4=Ozcelik|first4=Damla|last5=Schmidt|first5=Holger|last6=Hawkins|first6=Aaron R.|author6-link= Aaron Hawkins (engineer) |date=2016-01-01|title=Improved environmental stability for plasma enhanced chemical vapor deposition SiO2 waveguides using buried channel designs|journal=Optical Engineering|volume=55|issue=4|pages=040501|doi=10.1117/1.OE.55.4.040501|pmid=28190901|issn=0091-3286|bibcode = 2016OptEn..55d0501W |pmc=5298888}}</ref>