Polarization controlled tunable multiwavelength SOA-fiber laser based on few-mode polarization maintaining fiber loop mirror

A tunable multiwavelength fiber ring laser based on a semiconductor optical amplifier and few-mode polarization maintaining fiber (FM-PMF) loop mirror is proposed and experimentally demonstrated. It is accomplished by simply adjusting a polarization controller (PC) next to the FM-PMF in the loop arm for the polarization-dependent mode excitation in the FM-PMF and the resulting effective refractive index change. In addition, the undesirable dependence of the transmission loss of the FM-PMF loop mirror on the rotation angle of the PC in the loop arm can be reduced by using a fiber coupler with unequal coupling ratio instead of equal coupling ratio. Stable and tunable multiwavelength operation with up to 11 lasing lines at about 1.5 nm interval is achieved with the power deviation less than 2 dB and optical signal to noise extinction ratio over 35 dB.