Multiplexed identical-broadband-chirped-grating interrogation system for large-strain sensing applications

We report here a simple and low-cost technique for extreme strain measurement. The overlapping of a chirped sensor grating with an identical reference device provides a novel mechanism for measuring strain. This system permits a linear relationship between strain and resultant optical power. The maximum sensing range of the system is determined by the bandwidths of the gratings employed. A 20-nm chirped grating facilitates a sensing range up to 20 000 με. This paper also demonstrates an arrangement for multiplexing up to four gratings, which can be rapidly and truly simultaneously interrogated.