DISPERSION TUNING OF A LINEARLY CHIRPED FIBER BRAGG GRATING WITHOUT ACENTER WAVELENGTH SHIFT BY APPLYING A STRAIN GRADIENT

We propose a new method for controlling the chirp of a linearly chirpe d fiber Bragg grating (FBG) without a center wavelength shift by using beam bending. The beam consists of a plastic sleeve enclosing a 10-cm -long chirped FBG and a metal rod. The grating pitch could be varied t o give positive or negative chirp as well as zero chirp (i.e., uniform pitch) as applying displacement to one end of the beam without rotati on. The dispersion at the two extremes of mechanical displacement were -791 ps/nm and +932 ps/mn. The center wavelength shift of the FBG was as small as 0.09 nm over the dispersion tuning range.