Improving sensing properties of the long-period gratings by reactive ion etching

This work presents an application of reactive ion etching (RIE) for effective sensitivity tuning of the long-period gratings (LPGs). The technique allows for an efficient and well controlled etching of the fiber cladding and for achieving dispersion turning point of higher order cladding modes, where LPGs show the highest sensitivity to a number of influences. The effect of the etching on spectral properties of the LPGs is discussed. We correlated the decrease in fiber radius with the shift of the LPG resonance wavelength. The advantage of this approach is a capability for very repeatable post-processing of the LPGs with a remarkable precision.