Temperature-sensitive mechanical LPFG using contractive force of heat-shrinkable tube

A novel temperature-sensitive mechanical long period fiber grating (LPFG) fabricated utilizing the photo-elastic effect is proposed. Our proposed LPFG consists of a telecommunication optical fiber, a metric screw, and the heat-shrinkable tube, which are commercially available. The heat-shrinkable tube and the metric screw are used to obtain the grating along the single-mode fiber. The gratings are achieved by pressing the optical fiber between the heat-shrinkable tube and the metric screw due to the contractive force of its tube. By changing the temperature, the resonance loss is tuned due to the thermal expansion of the heat-shrinkable tube. Operating mechanism of thermally tunable characteristics of our LPFG are also described from a viewpoint of the coupling coefficient.

► Novel temperature-sensitive mechanical long period fiber grating (LPFG) is proposed.
► Thermal characteristics of LPFG can be controlled by using different kind of tube.
► The temperature characteristics of the LPFG is investigated experimentally.
► Its resonance losses and resonance wavelengths strongly depended on temperature.
► The thermal coefficients of resonance wavelength shift were more than 0.13 nm/°C.