Research On Stimulated Brillouin Scattering Slow Light In Optical Fibers And Optical Devices

In recent years, slow light based on stimulated Brillouin scattering(SBS) in optical fibers has attracted much more interests for its potential applications in optical buffering, data synchronization, optical memories and optical signal processing. Compared with previously demonstrated slow-light techniques, such as electromagnetically induced transparency (EIT) and coherent population oscillations (CPO), it has a lot of advantages:the high compatibility with the existing optical communication systems; tunable wavelength; low pump-power requirement. Slow light based on SBS in optical fibers has become a hot topic in the world.However, time delay is always very small and accompanied with serious pulse distortion under the influence of pump depletion (gain saturation) and amplified spontaneous Brillouin emission (ASBE). The parameters of optical fiber structure and Brillouin gain also affect the gain saturation process and influence the time delay and pulse distortion of SBS slow light. Based on the above facts, the coupled SBS equations are numerically solved by non-iterative backward difference and implicit finite difference with prediction-correction, the main conclusions are made as follows:1. When the Stokes bandwidth is much smaller than the Brillouin gain bandwidth, the time delay and the pulse broadening factor increase with the increasing gain in the small signal regime, but for pulse with the smaller gain bandwidth has a larger slope than the others. The pulse with smaller gain coefficient, smaller gain bandwidth and larger effective mode area reaches the gain saturation at a larger gain. In the gain saturation regime, the pulse with larger gain coefficient, smaller gain bandwidth, smaller effective mode area begins to decrease more quickly. At a given pump power whose gain parameter is in the small signal regime, the time delay and pulse broadening factor increase with the increasing gain coefficient, whereas decrease with the increasing gain bandwidth and effective mode area.2. The time delay will not decrease with the increasing gain bandwidth if the Brillouin gain bandwidth isn't much larger than the Stokes bandwidth, increasing the Brillouin gain bandwidth can increase the time delay when the Stokes pulse width isn't much larger than the acoustic lifetime.3. Tellurite fiber has a much larger time delay coefficient(1.8ns/dB) and reaches the gain saturation at a larger gain compared with the chalcogenide fiber, which is more advantageous to overcome the influence of gain saturation and has a larger time delay. At a given pump power, higher input Stokes power is more easily to reach the gain saturation and leads to a smaller time delay.