Changes in spectral properties of fibre bragg gratings owing to bending

The effects of bending on the spectral characteristics of fibre Bragg gratings have been investigated at relatively small bend diameters for small form factor applications. Tests undertaken on Bragg gratings written in different types of singlemode optical fibre indicate that the fibre type influences the magnitude of observed changes. Shifts in the centre wavelength of ~0.35~nm have been measured for a low bend loss fibre when the bend diameter was reduced to 6~mm. In contrast, no consistent trend could be observed for Bragg gratings in standard SMF-28 optical fibre as a function of bend diameter, despite the higher losses exhibited in this case.