Fig. 1. Transversal electrical field distribution of (a) LP01, (b) LP11, (c) LP21, and (d) LP02 modes. The arrows indicate the polarization state.

Fig. 2. (a) Experimental setup for the measurement of reflection spectra of the FM-FBG. Black line shows the SMF and blue line shows the FMF, respectively. (b) Measured reflection spectrum of the FM-FBG with hybrid mode injection. (c) Propagation constants of LP01, LP11, and LP21 modes, the dashed lines represent the average propagation constant of the neighboring modes.

Fig. 3. Schematic of the proposed multi-wavelength fiber laser based on FM-FBG.

Fig. 4. Output spectra of each single-wavelength operation.

Fig. 5. Output power versus pump power for the five single oscillating wavelengths.

Fig. 6. Output spectra of (a) dual neighbored wavelengths, (b) dual divided wavelengths, and (c) triple neighbored wavelengths.