Photonic bandgap narrowing in conical hollow core Bragg fibers

Journal Article · Mon Aug 18 04:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4893594· OSTI ID:22310859

Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet ^[1]; Bayindir, Mehmet ^[1]

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1. UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey)

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.

• OSTI ID: 22310859
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 7 Vol. 105; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
ABSORPTION SPECTRA
BRAGG REFLECTION
CLADDING
DIELECTRIC MATERIALS
FIBERS
LAYERS
REDUCTION
REFLECTION
SIMULATION
THICKNESS
TRANSMISSION
VISIBLE RADIATION
WAVEGUIDES
WAVELENGTHS