Flexible fabrication of long-period in-fiber gratings

Summary form only given. We have demonstrated a novel, simple, low-cost and all-fiber interrogation technique for a strain/temperature fiber Bragg sensor using a long-period grating. We show the schematic diagram of the demodulation scheme. The amount of light transmitted by the long-period grating is determined by its wavelength and is therefore proportional to the wavelength of the backreflected light from the fiber Bragg sensor acting as a spectral filter.