Occurrence of features of fiber Bragg grating spectra having a wavelength corresponding to the phase mask periodicity

Abstract

Use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, i.e. twice the Bragg wavelength, associated with the phase mask periodicity were observed. However, when phase mask orders other than ±1 were absent during fabrication the features at 1552 nm were not evident. Index Terms-fiber Bragg grating, double of the Bragg wavelength, phase mask, Talbot interferometer.

Variations of the growth of harmonic reflections in fiber Bragg gratings fabricated using phase masks

“…(1), as inferred [12] and reported in experiments [13,14]. Conversely, for writing with pure 1 diffraction orders in a Talbot interferometer arrangement, this second periodicity does not occur, and there are no grating features observed at twice the Bragg wavelength [15]. Grating resonance features of odd harmonics of this second periodicity, i.e., 2λ B ∕3 and 2λ B ∕5, have also been observed [16,17].…”

Effect of phase mask alignment on fiber Bragg grating spectra at harmonics of the Bragg wavelength

“…On the other hand, when just the 1 diffraction orders were present in an FBG writing arrangement involving a Talbot interferometer, features at twice the Bragg wavelength (expected near 1550 nm for Λ pm 536 nm) were not observed [14].…”

Understanding fiber Bragg gratings at harmonics of the Bragg wavelength through spectra and images

“…FBGs resonances in phase-mask-produced gratings have been observed at double the Bragg wavelength 12,13 and at several of the harmonics of either the Bragg wavelength or twice the Bragg wavelength, namely 2λ B /3, λ B /2 and 2λ B /5 10,14 . Conversely, when just the ±1 diffraction orders were present in a Talbot interferometer set-up features at twice the Bragg wavelength (near 1550 nm for Λ pm = 536 nm) were not observed 15 . Equations (2a) and (2b) show that reflections at λ B potentially arise from both of the periodicities, i.e.…”