Up to the 1552nd Order Passively Harmonic Mode-Locked Raman Fiber Laser

Abstract

An ultrahigh order passively harmonic mode-locked Raman fiber laser based on nonlinear polarization rotation has been proposed and demonstrated experimentally. Different orders harmonic mode-locking (HML) was observed from the first to the 1552nd order by changing the pump power with adjusting polarization states. Up to the 1552nd order HML, corresponding to the repetition rate of 587.2 MHz, was obtained with the output power of 168.3 mW. The stability of HML is attested by the supermode suppression level as large as 40 dB. Different from the pulse energy quantization in low-order HML, the mechanism of high-order HML contributes to the acoustic stabilization effect.