Online inter-modal dispersion monitoring based on four-wave mixing

A novel online Differential Mode Group Delay(DMGD)monitoring method based on four-wave mixing (FWM) in few mode fiber (FMF) transmission system is proposed, and the DMGD monitoring is achieved on the whole range of 15—50 ps/km. Detection principle is deduced and relationship of the power of idler waves and DMGD is analyzed. With various chromatic dispersion(CD) values, different line widths and different optical signal noise ratio(OSNR) values, the simulations are carried out. The simulation results show that this new DMGD monitoring method is less affected by different line widths and has a high tolerance for OSNR.