Photonic bandgap narrowing in conical hollow core Bragg fibers

Fahri Emre Ozturk, Adem Yildirim, Mehmet Kanik, Mehmet Bayindir

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightly smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.

Original languageEnglish (US)
Article number071102
JournalApplied Physics Letters
Volume105
Issue number7
DOIs
StatePublished - Aug 18 2014

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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