Numerical investigation of cladding mode overlap of evanescent waves with air channels in index-guiding photonic crystal fiber long-period gratings

Shijie Zheng*, Yinian Zhu, Sridhar Krishnaswamy

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The array of axially aligned air channels and the robust waveguide characteristics of index-guiding photonic crystal fibers (IG-PCFs) integrated with long-period gratings (LPGs) make them a powerful platform for chemical sensing and detection. Compared to their conventional all-solid fiber counterpart, the IG-PCFs are a particularly attractive sensing device as they are both a waveguide and a vapor/aqueous transmission cell, permitting light intensity-analyte interaction over long path length without the removal of fiber cladding. While the fundamental core-mode in the IG-PCF has been utilized for evanescent field based sensing, there exist two inherent limitations: (1) only short distance extended by evanescent waves from the guiding core to the surrounding PCF cladding air channels to restrict the probing of an analyte only in the inner most ring of the air channels in cladding, and (2) less than 1% power of the core-mode overlap with the surrounding air channels leading to weak light intensity-analyte interactions due to the localization of the coremode in the fiber core area. Should a cladding-mode with maximum overlap in air channels be excited by an LPG, it would fundamentally increase the evanescent field sensitivity. In this work, we present the simulation for the mode properties of selected IG-PCF for optimization of mode field distribution and light power overlap with air channels in fiber cladding. The numerical calculation reveals that if the optimized cladding-mode is selectively coupled, the evanescent wave overlap (at wavelength of 1550 nm) with cladding air channels of the round and hexagonal structures can be increased from 0.11% and 0.13% up to 4.01% and 6.54%, respectively.

Original languageEnglish (US)
Title of host publicationHealth Monitoring of Structural and Biological Systems 2010
Volume7650
EditionPART 1
DOIs
StatePublished - Jun 18 2010
EventHealth Monitoring of Structural and Biological Systems 2010 - San Diego, CA, United States
Duration: Mar 8 2010Mar 11 2010

Other

OtherHealth Monitoring of Structural and Biological Systems 2010
CountryUnited States
CitySan Diego, CA
Period3/8/103/11/10

Keywords

  • Evanescent waves
  • Fiber Bragg gratings
  • Fiber optic sensors
  • Long-period gratings
  • Photonic crystal fibers

ASJC Scopus subject areas

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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