Suppression of idler spectral broadening in highly efficient fiber four-wave mixing by binary-phase-shift-keying modulation of pump wave

Proposes and demonstrates a novel method of suppressing spectral broadening of the idler wave, which is generated in fiber four-wave mixing (FWM) pumped by a continuous wave. In this scheme, binary-phase-shift-keying (BPSK) modulation of the pump wave broadens the pump spectrum so that the Brillouin threshold for the pump power is increased, whereas it never affects the spectrum of the idler wave. By the 2-Gb/s BPSK modulation of the pump wave, we achieve a FWM efficiency as high as 10 dB, maintaining a side-band suppression ratio of the idler wave larger than 25 dB.