Generation and amplification of the ultrashort optical pulses in passive harmonic mode-locking Er3+-doped fiber laser

The experimental results of the stable high-order harmonic mode-locking pul ses generation and amplification in Er3+-doped fiber amplifiers is reported . Using nonlinear polarization rotation (NPR) effect, the artifical saturab le absorber is generated and the stable high-order harmonic mode-locking pu lses have been generated from Er3+-doped ring fiber laser (407.6 MHz repeti tion rate harmonic mode-locking has been obtained due to the limited bandwi dth of the osciloscope). Three different ways have been found, through whic h high-order harmonic mode-locking pulses have been generated. The stable 4 th harmonic mode-locking (83.52 MI-fi) pulses have been generated accompany ing with soliton side-band in the output spectra of the pulses. After the h igh concentration Er3+-doped fiber amplification (6 m in length, 2700 ppm), the 4th harmonic mode-locking pulses (83.52 MHz) are amplified to an avera ge power of 13.88 mW. The amplified pulses is of a pulse width 201 fs, with central wavelength of 1.531 mu m, single pulse energy of 0.166 nJ correspo nding to 0.811 X 10(3) W peak power, a gain of 19 dB with 83.52 MHz repetit ion rate.