As shown in Fig. 2 (a), the weak odd-order Stokes lines appear, which experience the power depletion during SBS process in SMF 2. Contrarily,
the intense even-order Stokes lasing lines are generated owing to
the Brillouin amplification in SMF 2.The measured OSNR is more
than 28 dB, and the peak power is about 3.5 dBm.