Abstract
We demonstrate the evolution of the Bragg gratings inscribed in Panda fibers with chemical etching. The resonance wavelengths can blueshift with cladding reduction similar to the conventional counterparts. But the wavelength separation between the two polarizations is co-determined by the stress and the asymmetric shape effects. The fast and slow axes of the fiber can be reversed with each other and zero birefringence can be achieved by chemical etching the structure. When the stress-applying parts of the fiber are removed, the finalizing grating can be exploited for the temperature-independent refractive index sensing, since the modes corresponding to the two polarizations exhibit the dissimilar responses to the external refractive index change but the same response to temperature. Our device is featured with easy achievement, spectral controllability, and relative robustness.
Highlights
Birefringent fiber Bragg gratings (FBGs) have been realized by introducing periodic index perturbations along birefringent optical fibers [1,2,3,4,5,6,7,8] or asymmetric index distributions along the cross sections of the standard optical fibers via the laser side-irradiation technique [9,10]
We demonstrate the evolution of FBGs inscribed in Panda fibers by chemical etching the structure
We demonstrate the evolution of the FBGs inscribed in Panda fibers with chemical etching
Summary
Birefringent fiber Bragg gratings (FBGs) have been realized by introducing periodic index perturbations along birefringent optical fibers (such as Panda, Bow-Tie, or asymmetric-shape fibers) [1,2,3,4,5,6,7,8] or asymmetric index distributions along the cross sections of the standard optical fibers via the laser side-irradiation technique [9,10]. A lot of works have been done to achieve highly RI sensitive FBGs with the chemical etching technique. Etched FBG sensors have been explored in the detection of external RIs [14,15,16,17,18,19,20], magnetic fields [21], bio-chemical agents [22], DNAs [23], and etc. Those previous works are mainly focused on studying of conventional FBG counterparts with no special stress. Our finalized structure can be exploited for the temperature-independent RI sensing, since the modes corresponding to the two polarizations exhibit the dissimilar responses to the external RI change but the identical response to temperature
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