PERFORMANCE OF STRAIN-FREE STIMULATED BRILLOUIN-SCATTERING SUPPRESSION FIBER

We have investigated experimentally the performance of an SRS suppress ion fiber with a nonuniform dopant concentration along its length fabr icated by the VAD method. We have achieved an SBS threshold of 15 dBm against a continuous wave at 1.55 mu m. This is 7 dB larger than that of conventional fiber. We have confirmed experimentally that the incre ase in the SBS threshold can he estimated from the ratio of the Brillo uin frequency shift change over the effective interaction length to th e intrinsic Brillouin gain bandwidth. Moreover, we have confirmed that there is no BER degradation after a transmission of 138 km through a 2.5 Gb/s intensity modulation direct detection system when the SBS sup pression fiber is used with an input power of 16 dBm.