Fig. 1. Experimental principle diagram

Fig. 2. Gain characteristic curve of SOA

Fig. 3. Experimental waveforms. (a) Probe light waveform; (b) control light waveform; (c) waveform of first reflected signal; (d) interference signal waveform

Fig. 4. Variation of nonlinear phase shift. (a) Variation of nonlinear phase shift with bias current under different probe light powers; (b) variation of nonlinear phase shift with bias current under different control light powers