Characteristics of noise-like pulse with broad bandwidth based on cascaded Raman scattering

A noise-like pulse (NLP) with broadband emission spectrum and superior beam quality from a dispersion managed mode-locked Yb-doped fiber laser has been demonstrated based on stimulated Raman scattering. After insertion of a 150 m long single mode fiber into the laser cavity, the second order stoke wave from 1.3 MHz repetition rate of NLP can be excited. With a 320 mW pump power, the highest pulse energy of NLP was about 35.1 nJ and the emission spectrum was extended from 1000 to 1160 nm. Through a multi-mode fiber laser, the broad bandwidth NLP can produce relatively low speckle noise imaging with contrast below 0.04. The generated NLPs can be used as a superior light source for the biomedical diagnosis and laser projection in the near future.