Stimulated Brillouin scattering (SBS) is one of important nonlinear effects in optical fiber communication systems. Due to its low threshold, it limits the optical power that couples into the fiber. In this paper, Stimulated Brillouin scattering and the effect of phonon loss to SBS in optical fiber communication systems are investigated. In experiments we measure first the power of backward Stokes wave and output light under various input powers of the systems with different lengths of fibers. Then for observing the effect of the phonon blocker to the SBS threshold, we repeat the same experiments but with a phonon blocker inserted at different locations of the fiber link. The experiments indicate that adding phonon blocker to the fiber is able to increase the SBS threshold, and the blocker at different locations makes different effects.
Polarization dependent characteristics of the fiber-optic transmission systems become more important than ever before as the bit rates increase to 10 Gb/s and beyond. We derived the Jones matrix and Muller matrix of a polarization controller (PC), and in our experiment, we can get every wanted state of polarization (SOP) at the PC output with all kinds of input SOP. Using PC as a key component, we designed a polarization stabilizer. With the unknown change of the input SOP and random shift of the environment, the polarization stabilizer can maintain a fixed SOP through controlling the PC in real-time.
It is important to know how the degree of polarization (DOP) changes with differential group delay (DGD) when DOP is the feedback parameter for an adaptive polarization mode dispersion compensator (PMDC). We derived the mathematical expression of DOP for pulse sequence with arbitrary and Gauss waveforms under the condition of quasi-monochromatic wave, then analyzed theoretically the relation between DOP and DGD with different power splitting ratio and pulse width. Then we carried out the experiments of DOP with 10Gbit/s RZ/NRZ pseudo random sequence pulses and made comparison between theoretical calculation and experimental data. The comparison showed that they matched closely. We also verified by experiments that DOP is independent of fiber dispersion.