Effect of TiO2 nano-overlays deposited with atomic layer deposition on refractive index sensitivity of long-period gratings

This paper we discusses an effect of coating long-period gratings (LPGs) with a thin titanium dioxide (TiO₂) overlays on refractive index (RI) sensitivity of the LPG. The overlays have been obtained using atomic layer deposition (ALD) method. The method allows for deposition well-controlled in thickness, well defined in optical properties, high-RI and very conformal thin films as required for optical fiber sensors. For the investigated LPGs we obtained sensitivity of 3490 to 6471 nm per RI unit depending on range RI.