In this paper, we demonstrate point-by-point inscription of eccentric fiber Bragg grating (EFBG) in conventional single-mode fiber (Corning SMF-28) with second-order Bragg resonances within the C-band using an IR femtosecond laser. Highly localized fiber Bragg gratings can be inscribed point-by-point with focused ultrashort pulses. EFBGs are localized close to the core-cladding interface, yielding strong cladding mode resonance couplings and high photoinduced birefringence. The inscription conditions to optimize the grating fabrication have been explored to achieve second-order resonances of good spectral quality. Potential applications of EFBG in refractometry sensing are further illustrated. Two interrogation techniques for EFBG in refractometry are reported and experimentally tested.
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| http://dx.doi.org/10.1364/AO.58.000528 | DOI Listing |
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