Performance enhancement of long period fiber gratings for strain and temperature sensing

We will discuss performance optimization of strain and temperature sensors based on long period fiber gratings (LPFGs) through control of the temperat ure sensitivity of the resonant peak shifts. Distinction between the effect s of strain and temperature is a major concern for applications to communic ation and sensing. This was achieved in this work by suppressing or enhanci ng the temperature sensitivity by adjusting the doping concentrations of Ge O2 and B2O3 in the core or cladding. The LPFGs were fabricated with a CO2 l aser by the mechanical stress relaxation and microbending methods. The opti mized temperature sensitivities were 0.002 nm/degrees C for the suppressed case and 0.28nm/degrees C for the enhanced case, respectively. These LPFGs were used for simultaneous measurement of strain and temperature. The resul t indicates the rms errors of 23 mu strain for the strain and 1.3 degrees C for the temperature.