a pulse width tunable fiber-based chirp pulse amplification (cpa) system had been built by our newly developed dispersion tuning mechanism. in order to realize dispersion fine tuning, we changed the temperature of chirped fiber bragg grating (cfbg), which was used as stretcher in cpa system, to change the dispersion compensation level between stretcher and grating pairs compressor. by the help of this method, the minimum pulse width after compression can be obtained by balancing the dispersion of the stretcher and of the compressor. in our experimental fiber cpa system, the minimum pulse duration of 780 fs was recorded by autocorrelator during the cfbg temperature tuning at temperature range of 0 degrees c to 50 degrees c, and the pulse tuning accuracy can reach about 3 fs/degrees c. (c) 2016 elsevier gmbh. all rights reserved.