Abstract

In this paper we have investigated optical frequency-shift sensitivities of the transmittance channeled spectra of cascaded-chirped long period fiber gratings (C-CLPGs) to the applied strain and temperature change from the viewpoint of the sensor use. In the experiment, several kinds of C-CLPGs have been fabricated by changing the cascaded distance between CLPGs and the strain- or temperature-induced spectral shifts for three different order of the cladding modes are measured simultaneously by use of a cross-correlation technique which provides highly precise determination of the spectral shift. As a result, it is confirmed that the frequency-shift sensitivities of the C-CLPGs to the strain and temperature are larger with the higher order of cladding mode, while the dependences for the temperature sensitivity is much less than that for the strain. In addition, the dependences for the cascaded distance are also investigated.

© 2020 The Author(s)