Temperature Compensation of Long Period Fiber Grating with Negative Strain Coefficient

A passive temperature-compensating package of Long Period Fiber Grating (LPFG) was designed based on its negative strain coefficient. LPFG was pasted on the substrate material, such as copper and Plexiglas, under tension. The strain induced by the thermal expansion of substrate material was used for temperature compensating. The experimental results showed that the mounted grating on copper exhibited lower temperature sensitivity (about 78pm/degrees C), compared with uncompensated grating(about 118pm/degrees C). But the transmission spectrum waveform of the mounted grating on Plexiglas changed. It was demonstrated that this package could improve the wavelength stability of LPFG when appropriated substrate material was chosen.