【作者】 赵军发；

【导师】 赵启大； 杨秀峰；

【作者基本信息】 南开大学 ， 光学， 2010， 博士

【摘要】 受激布里渊散射(Stimulated Brillouin Scattering, SBS)是泵浦光、斯托克斯光通过声波进行的非线性过程。光纤中的SBS所需要的阈值远低于受激拉曼散射(SRS),是光纤中的主要非线性现象。光纤中的SBS非线性效应,在相位共轭、光纤传感、微波光子学、光可控延迟以及光纤激光器等方面有着广泛的应用。光纤中基于SBS的可控慢光因为具有功率阈值低、群速度延迟易控、工作波长可调谐、易于同现有光网络集成等优点,是光纤中慢光研究的热点。可调谐多波长布里渊掺铒光纤激光器将光纤中的SBS非线性放大同掺铒光纤的线性放大相结合得到室温稳定的多波长输出,具有波长间隔一致、线宽窄、功率谱相对平坦等优点。本论文是在天津市自然科学基金(No.08JCYBJC14400),天津市科技支撑重点项目(No.07ZCKFGX00200),国家自然科学基金资助项目(NO.60572018)的支持下完成的。主要内容包括：1.对光纤中基于SBS的可控慢光和基于SBS的多波长掺铒光纤激光器的研究进展进行了系统介绍。对光纤中SBS机理进行了阐述,并从SBS耦合波方程出发,理论研究了光纤中基于SBS的慢光和快光。对SBS慢光延迟的稳态小信号解析解进行了理论研究。2.对高非线性光子晶体光纤作为SBS慢光介质进行了研究。通过理论分析得到,具有小模场面积的光子晶体光纤作为慢光介质可以提高慢光系统的延迟效率。实验结果表明,在高非线性光子晶体光纤作为慢光介质的系统中,50 ns脉冲信号获得了33 dB的布里渊增益,脉冲延迟了30 ns,延迟效率达到了0.0046 ns/mW/m,是普通单模光纤的13.7倍。3.设计研制了一种新型的环形腔可调谐多波长布里渊掺铒光纤激光器。提出利用一个3 dB耦合器的两端连接增益介质,并结合另一个端口的光纤环镜形成反馈、实现级联的结构,简化了激光器结构、降低了腔内的损耗。双向布里渊泵浦结构有效的降低了激光器阈值功率和加强了多波长的产生。在1480 nm最大泵浦功率110 mW时,激光器获得了13 nm调谐范围内平均21个波长的输出。4.设计研制了一种基于光子晶体光纤的可调谐多波长布里渊掺铒光纤激光器。激光器采用结构简单的环形腔,用一个耦合器实现布里渊泵浦光的导入和多波长激光的输出。利用70 m长的低损耗的高非线性光子晶体光纤作为布里渊增益介质,缩短了腔长,便于集成。在布里渊泵浦信号3 dBm,1480 nm泵源泵浦功率30 mW情况下,获得了可调谐范围25 nm的3波长激光输出。当1480 nm泵源泵浦功率增加到最大110 mW时,实现了调谐范围10 nm,波长间隔为0.078 nm的10个波长激光输出。5.设计研制了环形和线形宽带可调谐多波长布里渊掺铒光纤光源。提出利用光纤中的SBS效应产生反方向传输的斯托克斯信号将光信号返回腔中的结构,消除了腔内自激模的影响,使光源的调谐带宽仅由掺铒光纤放大器的带宽和布里渊泵浦信号的调谐范围决定。其中,线形结构采用布里渊泵浦信号前置双次放大的结构,有效降低了阈值功率。光源实现了1530-1570nm之间40 nm可调谐范围的多波长输出。更多还原

【Abstract】 Stimulated Brillouin scattering (SBS) is a nonlinear interaction between the pump and Stokes fields through an acoustic wave. SBS is the major nonlinear optical phenomena in optical fibers because the threshold powers are much lower than those needed for stimulated Raman scattering (SRS). SBS has wide applications in phase conjugation, optical fiber sensors, microwave photonics, controllable slow light and fiber lasers.Slow light based on SBS has already becomes a hot topic in the research of slow light, as it has many advantages such as low Brillouin threshold power, easily controllable group velocity, tunable wavelength and it is easy to be integrated with existing telecommunications. Tunable multiwavelength Brillouin erbium-doped fiber laser (MWBEFL) takes the advantages of Brillouin amplification in optical fibers and high gain from the erbium-doped fibers amplifier (EDFA). It has the merits of equal-wavelength spacing, narrow linewidth and high output uniformity over the channels at room temperature.With the subjects supported by the Tianjin Natural Science Foundation (Grant No.08JCYBJC14400), the Tianjin Key Project of Applied and Basic Research Programs (Grant No.07ZCKFGX00200), the National Natural Science Foundation Project (Grant No.60572018), the main contents of this paper are as following:1. The advancements on controllable slow light and multiwavelength erbium-doped fiber lasers based on SBS are introduced systemically. The physical principle of SBS in optical fibers is presented and the SBS slow and fast light in optical fibers are theoretically studied from the SBS coupled wave equations. The analytic solutions of SBS slow light delay time are theoretically studied in the case of stable state with small-signal.2. The highly nonlinear photonic crystal fiber used as SBS slow light medium is studied. Through theoretical analysis, the photonic crystal fibers with small mode field areas can improve the delay efficiency of the slow light system. This is demonstrated by the experiment. The Brillouin gain of 33 dB is achieved when a highly nonlinear photonic crystal fiber is used as slow light medium, which results in 30 ns time delay of 50 ns signal pulses. The delay efficiency of this kind fiber is 0.0046 ns/mW/m, which is about 13.7 times larger than the single mode fiber.3. A new type of simple tunable multiwavelength Brillouin/erbium fiber ring laser is presented. It is proposed that two ports of a 3dB optical coupler is employed to connect the gain medium, in combination of a fiber loop mirror in another port to form feedback and realize cascade. This configuration reduces the insertion loss and complexity of the fiber laser. The threshold power is greatly reduced and the generation of multiwavelength is enhanced by the bidirectional pumping scheme. With the maximum 1480 nm pump power of 110 mW,21 average output channels with 13 nm tuning range are achieved.4. A tunable multiwavelength Brillouin/erbium fiber laser based on highly nonlinear photonic crystal fiber is presented. The ring cavity is very simple, in which one coupler launches the Brillouin pump signal into and takes the multiwavelength signals out of the cavity. The laser with shorten cavity length is easy to be integrated due to a 70-m low loss highly nonlinear photonic crystal fiber (HNL-PCF) used as the Brillouin gain medium. The laser provides a tuning range of 25 nm and 3 output channels at the Brillouin pump power of 3 dBm and the 1480 nm pump power of 30 mW. At the maximum 1480 nm pump power of 110 mW,10 stable output channels with 10 nm tuning range are achieved.5. Widely tunable multiwavelength Brillouin/erbium fiber sources with ring and linear cavity are demonstrated. The structure is proposed that the Brillouin Stokes signals return back to the linear cavity owing to the effect of SBS. The influence of the self-lasing cavity modes is effectively eliminated. The tuning range of the fiber sources is only limited by the bandwidth of erbium-doped fiber amplifier and the tuning range of Brillouin pump signal. The threshold power of the linear fiber source is effectively reduced by the double-pass Brillouin pump preamplified technique. The fiber sources provide a tuning range of 40 nm from 1530 nm to 1570 nm.更多还原