Research Of Slow Light Based On Stimulated Brillouin Scattering

With the wide application of fiber, optical communications develop rapidly. In the evolution of telecommunications of high-speed and broadband index, the processing of optical signal begins exploration in the optical domain. Currently and widely applicable optical devices make use of electronic signal processing technique, through optical-electronic conversion. Due to deficiency of optical-electronic conversion and device compatibility, optical devices are required in optical devices, expecting manipulating optical signal directly in optical domain, to obtain performance improvement of entire telecommunication system. In telecommunication signal processing, route and buffer are characteristics of highly importance, so research of optical buffer and optical storage emerge naturally.Slow light is considered one of promising techniques of many optical storages schemes. In almost recent decade, research groups home and abroad conduct research of slow light in depth. The physical mechanism lies in slow light can be described as a gain window process imposed by external field. This gain window generates rapid variation of refractive index or phase via Kramers-Kronig (K.K) relations. Through relations of group velocity and refractive index, slowing down of group velocity can be deducted then slow light phenomenon is generated.From the perspective of different mechanisms to generate gain window induced by optical field in medium, there are mechanisms of electromagnetically induced transparency (EIT), coherent population oscillations (CPO), coherent resonant induced transparency (CRIT), stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), optical parametric amplification (OPA), etc. From the perspective of different media, there are media of condensate sodium atom vapor, fiber, photonic crystal, waveguide, etc. Owing to advantages such as low threshold, room temperature, continuous tunability of wavelength, SBS slow light is considered as one of the most promising schemes.In this thesis, the conducting work of the research of slow light based on SBS is covered consequently, mainly in the medium of fiber. Relative theory and experiment works are developed, from setup of SBS slow light in fiber. Works include firstly calculating limitations of SBS slow light delay in theory and simulation. Secondly, research of high-resolution devices is carried out to meet the requirement of Brillouin parameter measurement and broadening gain spectrum window, including optical analysis and optical filter based on SBS. Finally, explore a means to realize SBS slow light delay and analyze its performance in system of comparatively low-resolution devices, to improve its feasibility of application. The key technique in our research is making use of SBS gain window, leading to dramatic variation of phase, and slowing down signal light, the so-called slow light.In this thesis, with the theme of SBS slow light, four innovative research works are progressing.1. Discuss delay limitations in SBS slow light system, and analyze its optical storage delay performance. By using simulation model based on K.K. Relations, calculate delay performance of isolated pulse and BPSK code. In conventional SBS slow light system of32dB maximum gain and500MHz broadband gain window,2.5ns-width isolated pulse is maximum delayed2.3ns (0.9bit), maximum delay of500MHz BPSK code is2.1ns (1bit), with their delay-bandwidth-products are1.2and1.1respectively.2. Due to requirement of measurement of parameter Brillouin gain window in SBS slow light system, explore an all-optical scheme of high-resolution optical analysis. The resolution can be as high as10MHz and the rejection ratio is33.5dB. Also by this means, measure spectrum of the practical subcarrier-multiplexing signal (quasi-OFDM signal).3. Owing to requirement of flat-top and high rejection ration profile of gain window, synthesized with SBS polarization scheme, a all-optical high-resolution filter scheme is proposed. The filter characteristics from the broadband gain spectrum are broadband width tunable250MHz to1GHz; flat-top uniform jitter1.5dB; selectivity44dB.4. Explore a means, to realize system setup in comparatively-low resolution devices, to effectively reduce requirement of experiment devices index and improve feasibility of application. The monitor unit of Heterodyne method effectively reduces device index requirement in slow light system.32ns maximum delay is achieved in laser of wavelength tunability of lpm. Fractional delay of0.1bit, delay-bandwidth-product of0.96, and delay-gain-ratio of0.80ns/dB are obtained.