Numerical analysis of refractive index sensitivity of long-period gratings in photonic crystal fiber

Yinian Zhu, Zonghu He, Jiří Kaňka, Henry Du

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

The modal coupling properties and resonance spectral response of long-period gratings (LPGs) in index-guiding photonic crystal fiber (PCF) are numerically investigated with respect to its sensitivity to changes in the index of refraction of the measurand in the PCF air channels using a full-vectorial mode solver combined with frequency-domain method. We show that the shift of wavelength resonance of a PCF-LPG structure can be extremely sensitive by appropriately designing the cladding air-channel dimension and geometry as well as the periodicity of the LPG inscribed in an endlessly single mode PCF (ESM-PCF-LPG). Specifically, a sensitivity of 4.3 × 10-8 refractive index unit (RIU) can be obtained in a refractive index range of 1.33 and 1.4 using an ESM-PCF-LPG with hexagonally arrayed 4-ring air channels at the grating periodicity of 1300 μm. A sensitivity of 4.1 × 10-7 RIU can be achieved in the range of 1.0-1.25 employing an ESM-PCF-LPG with similarly arrayed but 5-ring air channels at the grating periodicity of 350 μm. The predicted index sensitivity, coupled with other schemes for selectivity and specificity, opens the ESM-PCF-LPG structure for a variety of sensing and detection applications.

Original languageEnglish
Pages (from-to)99-105
Number of pages7
JournalSensors and Actuators, B: Chemical
Volume129
Issue number1
DOIs
StatePublished - 29 Jan 2008

Keywords

  • Fiber Bragg grating
  • Fiber-optic refractive index sensor
  • Long-period grating
  • Photonic crystal fiber
  • Refractometer

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