Exploration of higher-order mode coupling in long-period gratings for sensitive monitoring of polyelectrolyte self-assembly at nanoscale

Fei Tian, Jiri Kanka, Xiangzhi Li, Henry Du

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

4 Scopus citations

Abstract

Layer-by-layer (LbL) self-assembly via hydrogen bonding is one of the primary mechanisms to achieve stimuliresponsive polyelectrolyte thin films for a variety of applications. The ability to monitor the individual LbL steps in situ is of great significance in the development and understanding of hydrogen-bonded LbL systems of new design functions and properties. Long-period gratings in single-mode fiber (SMF-LPG) has the potential for such application by virtue of its high index sensitivity. We report a theoretical and experimental investigation to sort out the coupled cladding mode that is most sensitive to molecular adsorption events during LbL deposition. We have undertaken a combined theoretical and experimental investigation to illustrate and demonstrate the strong correlation between the order of the coupled cladding modes in long-period gratings (LPG) in conventional single mode fiber and their sensitivity to the process of layer-by-layer (LbL) assembly of polyelectrolyte multi-layers. We show that high-order cladding modes such as LP0,10 in LPG are significantly more sensitive than their lower-order counterparts such as LP0,2, with LP0,10 yielding a shift of 1.575 nm in resonance wavelength per polyelectrolyte repeating unit of poly(vinyl pyrrolidone)/poly(methacrylic acid) bi-layer. We illustrate the potential utility of SMF-LPG integrated with stimuli-responsive LbL thin films as sensors. The integrated LPG/LbL strategy as a robust LbL test-bed has broad ramifications in exploring and exploiting sensors and devices enabled by versatile, stimuli-responsive polyelectrolyte thin films.

Original languageEnglish
Title of host publicationFiber Optic Sensors and Applications XI
DOIs
StatePublished - 2014
EventFiber Optic Sensors and Applications XI - Baltimore, MD, United States
Duration: 8 May 20149 May 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9098
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceFiber Optic Sensors and Applications XI
Country/TerritoryUnited States
CityBaltimore, MD
Period8/05/149/05/14

Keywords

  • Long-period grating
  • layer-by-layer self-assembly
  • mode coupling
  • polyelectrolyte
  • single mode fiber

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