Fabrication of fiber gratings using a heating process

We demonstrate that a multichannel fiber grating can be fabricated using a heating method based on differences in the thermal expansion of the phase mask and the fiber. The separation between two neighboring channels in a multichannel grating can be precisely tuned by means of temperature control. A three-wavelength-channel equal-spacing grating is implemented under three different temperatures of 25, 160, and 300°C, respectively. In addition, a chirp fiber grating is manufactured, whereby the temperature gradient is adjusted to obtain an increased, adjustable bandwidth, which can be used in optical filter applications.