Response of fiber Bragg grating transmission dips at twice the Bragg wavelength to transverse strain

摘要

The effect of transverse strain on a fiber Bragg grating fabricated using a phase mask with 536-nm pitch has been investigated through the study of its reflection and transmission features at twice the Bragg wavelength near 1552 nm, that are due to reflection/transmission from FBG periodicities associated with the phase mask periodicity. The occurrence of two peaks in the reflection spectrum is due to the interleaved refractive index modulations along the fiber core, with the periodicity of the phase mask that produces a type of π-phase-shifted grating. The response of these features to transverse strain is similar to that observed previously for features at 2/3 of the Bragg wavelength that also arise from the same complex refractive index structure.