Management And Controltechnologies Of Slow-light Time Delay In Optical Fibers Via Stimulated Brillouin Scattering

Reducing the propagation velocity of the light is called slow light. Slow light is one ofthe crucial technologies to achieve optical buffering for future all-opticalcommunication system. The research on slow light can be dated back to1980s.Among several methods for achieving slow light, stimulated Brillouin scattering (SBS)in fibers has become a hot topic due to its advantages, including the room-temperatureoperation, the low Brillouin threshold, the wavelength tunability and the goodcompatibility with the available communication system.In this thesis, we focus on investigating the slow light based on SBS in opticalfibers, the main contents and innovation ideas of the paper are as follows:1. Based on controlling the polarizations of the pump and Stokes beams in apolarization-maintaining optical fiber, a simple scheme for enhancing the stabilityof the SBS interaction and the SBS slow-light time delay is proposed. Thepolarization state of the optical field in fibers changes easily due to thebirefringence and the environmental factor, any temporal and spatial changes inthe polarization state in practice doom to affect the stability of SBS interaction.While the scheme we proposed can overcome this problem. Apolarization-managed SBS slow-light experimental setup is establishedaccordingly, we measured the Brillouin gain spectrum for the fiber slow-axis, theBrillouin frequency shift is10.508GHz, the Brillouin gain bandwidth is38.43MHz, and the gain coefficient is g0=1.2425×10-11m/W. Also, a tunable time delayof0.82ns/dB is demonstrated for a Gaussian pulse with a width of88.9ns. Wecompare the experimental results with the polarization management and thatwithout the polarization management. The experimental results indicate that underthe polarization management, the maximal fluctuation of Brillouin gain and that oftime delay can be suppressed more than two times as compared to that without thepolarization management. 2. A multichannel, wide range and continuously tunable SBS slow-light time-delayline is proposed based on the intrinsic transmission delay of fiber with differentlength and the SBS effect, an experimental setup is established accordingly. Thedelay element is constructed by connecting a2-km single mode fiber (SMF) tofive short SMFs via two1×5optical switches. The five short SMFs are with anequal increment in length. By choosing different channels of the optical switchesone selects different length of the short SMFs. At the same time, assisted bytuning the power of the pump beam, a wide range and continuously tunable SBSslow-light time-delay line is achieved with the time delay from0to201.29ns.