Transmission limitations in coherent optical systems due to nonlinear effects in fibers

Abstract

The increased sensitivity provided by coherent optical detection is seen as a powerful way of extending the range of optical communication systems.Narrowband laser light is essential for coherent systems, but the maximum power that can be transmitted is limited by stimulated Brillouin scattering (SBS). Although SBS in fibers has been known for some time (1,2), it is only with the advent of single mode fibers having tight lateral confinement (4-8μm), low loss (0.2dB/km at 1.55μm) and long interaction length (>10km) that SBS now presents a potentially serious problem. The possible effects include a loss that increases with launched power resulting in saturation of the transmitted power, backward coupling of the SBS light into the laser and multiple frequency shifts.The increased sensitivity provided by coherent optical detection is seen as a powerful way of extending the range of optical communication systems.Narrowband laser light is essential for coherent systems, but the maximum power that can be transmitted is limited by stimulated Brillouin scattering (SBS). Although SBS in fibers has been known for some time (1,2), it is only with the advent of single mode fibers having tight lateral confinement (4-8μm), low loss (0.2dB/km at 1.55μm) and long interaction length (>10km) that SBS now presents a potentially serious problem. The possible effects include a loss that increases with launched power resulting in saturation of the transmitted power, backward coupling of the SBS light into the laser and multiple frequency shifts.