Optics and Photonics Society of Iran

In this paper , numerical simulation of pulse spectrum evolution in ring cavity of femtosecond fiber laser with all normal dispersion has been performed. In these kind of femtosecond fiber lasers spectral filtering of the chirped pulse in laser ring cavity, is the major component of mode locking and pulse shaping. Investigating of different effective parameters in the cavity results in acomulated nonlinear phase shift, the bandwidth of spectral filter and the cavity net group velocity dispersion are key parameters in determination of the shape and band width of output spectrum of these type of femtosecond fiber lasers. The result can be used for optimized design of femtosecond fiber lasers.