Optical fibre Bragg gratings for high temperature sensing

The development of new techniques for writing and tailoring the properties of Bragg gratings has generated a suite of distinct grating types that are optimised for performance within different temperature windows. These cover gratings produced by recipes such as hypersensitisation, thermal processing and single and multiphoton writing. In this paper, we review four types of high temperature gratings that offer comprehensive coverage of temperature space for most applications of interest. Up to 1200°C novel processing methods allow standard silica-based optical fibres to be used. However, beyond these temperatures, optical fibres made from other materials, such as sapphire, need consideration.