Spectral tuning of Microstructured Optical Fibre Bragg gratings utilizing ferrofluids

In the work presented here, a commercially available hydrocarbon ferrofluid is infiltrated into the capillaries of a double mode Microstructured Optical Fibre (MOF) in which a Bragg grating has been previously inscribed, for the development of a tuneable microstructured optical fibre device. Spectral measurements performed show that, when the ferrofluid is translated along the grating area using a static magnetic field, the reflected signal corresponding to the 0^th guiding mode is attenuated by ≈ 80%, while that corresponding to the 1^st order guiding mode is completely vanished in strength. In addition to the extinction ratio changes, spectral shifts of 0.1 nm and 0.23 nm are observed for the 0^th and 1^st guiding mode respectively.