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 0th guiding mode is attenuated by approximate to 80%, while that corresponding to the 1st 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 0th and 1st guiding mode respectively.