Highly-compact, temperature-insensitive phase-shifted and multiple phase-shifted long-period fiber gratings by use of a CO2 laser

We demonstrate the first fabrication of highly-compact and temperature-insensitive phase-shifted and multiple phase-shifted long-period gratings using the focused pulses Of CO2 laser with point-by-point technique. By introducing the 3pi/2, pi, or pi/2 phase shifts in the different location of the gratings with 480 mum of a period-length and total number about 16-21 periods, the symmetrical and asymmetrical pandpass filters based on those gratings can be obtained. The temperature sensitivity of formed gratings is about 8.8 pm/C-degrees at a temperature range of 23 degreesC - 190 degreesC. Such fiber grating component could be used as an all-fiber oscillator in the laser cavity. Long-period gratings with different phase shifts are also investigated with various notches of resonance attenuations. All gratings fabricated are compactness to be packaged into the fiber-optic based devices.