Passively mode-locked Ho-doped fiber laser with soliton rain and noise-like pulse regime

Abstract

A passively Ho-doped fiber laser at 2 μm with soliton rain and noise-like pulse (NLP) operation regime has been realized by using nonlinear polarization rotation (NPR) technology. By adjusting the polarization state, the evolution phenomenon of soliton rain pulse and the NLP are obtained. The typical NLP mode-locking operation regime is achieved by finely adjusting pump power and polarization state, which delivers a corresponding pulse energy of 8.93 nJ with pulse width of 1.31 ps. The soliton rain operation regime with multiple solitons is achieved by finely adjusting pump power, which delivers a corresponding pulse energy of 22.98 nJ with pulse width of 1.21 ps. In addition, a NLP mode-locking operation regime is obtained again under a proper pump power and polarization state with a corresponding pulse energy of 34.14 nJ and pulse width of 1.18 ps. The experimental results well demonstrate the evolution of ultrashort pulse regime with the pump power and polarization state in passively mode-locked Ho-doped fiber lasers at 2 μm.