受激布里渊散射光脉冲波形的研究

从实验和理论上研究了受激布里渊散射(SBS)光脉冲波形.在Nd∶YAG调Q激光器中实验研究了SBS光脉冲波形随抽运光参数、结构参数和介质参数的变化规律，并利用SBS理论模型进行了数值模拟，实验与数值模拟结果的变化趋势基本一致.结果表明，抽运光能量越小，透镜焦距越短，镜-池间距越长，介质声子寿命越长，SBS光脉冲波形就越不容易出现调制现象.分析和讨论了抽运光参数、结构参数和介质参数对SBS光脉冲波形的影响机理. 关键词： 受激布里渊散射 脉冲波形 抽运光参数 结构参数     

Perturbation approach to time resolved stimulated Brillouin scattering

The laser beam intensity changes, due to time resolved stimulated Brillouin scattering, were studied analytically using perturbation approach. It was shown, that the derived expressions enables a qualitative understanding of the previously reported results of the experimental as well as numeric investigations.     

A lidar system based on stimulated Brillouin scattering

The effect of stimulated Brillouin scattering in remote sensing of the ocean is investigated. It shows that by means of stimulated Brillouin scattering the signal-to-noise ratio of Brillouin lidar can be increased greatly by about 50 times, and its depth resolution can be improved to 1/8 of that with spontaneous Brillouin scattering. PACS 42.68.Wt; 42.79.Qx; 42.65.Es     

Investigation on the effect of beam divergence angle upon output waveform based on stimulated Brillouin scattering optical limiting

This paper investigates the effect of beam divergence angle on output waveform based on stimulated Brillouin scattering optical limiting. Output waveforms in the case of different pump divergence angles are numerically simulated, and validated in a Nd:YAG seed-injected laser system. The results indicate that a small pump divergence angle can lead to good interaction between pump and Stokes, and a platform can be easily realized in the transmitted waveform. In contrast, a peak followed by the platform appears when the divergence angle becomes large.     

Measurement of stimulated Brillouin scattering （SBS） threshold based on waveform variation of SBS optical limiting

This paper proposes a method for measuring the stimulated Brillouin scattering (SBS) threshold based on waveform variation of SBS optical limiting. The output waveforms for different pump power densities are numerically simulated, and validated in the Nd:YAG seed-injected laser system. The results indicate that SBS does not take place in the case of a low pump power density and thus the output power scales up linearly with pump power. Once the pump power density exceeds the SBS threshold, SBS takes place and thereby the energies are transferred from pump to Stokes. As a result, a small shoulder appears in the trailing edge of the output waveform, which provides another method to determine the SBS threshold.     

受激布里渊放大光脉冲波形的研究

利用瞬态包含抽运抽空的SBS理论模型对布里渊放大器进行了数值模拟，给出了脉冲波形随 抽运光功率密度和种子光与抽运光能量比的变化规律，并用实验进行了验证，理论与实验符合得较好. 关键词： 布里渊放大器 脉冲波形 脉宽     

Real time measurement of the attenuation coefficient of water in open ocean based on stimulated Brillouin scattering

A new method for measuring the attenuation coefficient of seawater in real time is suggested based on stimulated Brillouin scattering. The measurement can be achieved through detecting the intensity of back scattered stimulated Brillouin scattering and the intensity of the laser beam. PACS 42.68.Wt; 42.79.Qx; 42.65.Es     

高非线性微结构光纤中基于受激布里渊散射的慢光延迟

全光连续可调的慢光技术在全光网络和光信息处理等领域具有重要的应用前景. 利用自行设计并拉制的高非线性微结构光纤, 实验研究了基于受激布里渊散射的可调谐慢光延迟. 采用单抽运光和单级延迟方案, 当抽运光功率为162.6 mW时, 在长度为120 m的高非线性微结构光纤中获得了最大76 ns的延迟量, 相当于0.76个脉冲宽度. 通过调节抽运光功率的大小, 可以实现对慢光延迟量的可调谐.该慢光延迟方案具有延迟量大、 全光可调谐及与现有光通信系统兼容等优势. 关键词： 慢光 微结构光纤 受激布里渊散射     

Frequency domain aperture for the gain bandwidth reduction of stimulated Brillouin scattering

In this Letter, we propose a novel method based on the inhomogeneous Brillouin gain saturation to reduce the gain bandwidth significantly below its natural value. Based on our first experiments, we report a decrease of the bandwidth in a standard single mode fiber down to 3 MHz.     

Measurement of intrinsic Brillouin linewidth of fibers based on stimulated Brillouin scattering slow light

Intrinsic Brillouin linewidth is one of the essential parameters to optimize the gain spectrum of stimulated Brillouin scattering (SBS). A novel method for the measurement of the intrinsic Brillouin line-width based on SBS slow light is proposed and demonstrated. In this method, an implicit model based on the transient SBS theory is developed, and a data processing method is designed to obtain the value of the intrinsic Brillouin linewidth from the model. The measured results show that the method is effective for studying SBS slow light.     

Low-power phase conjugation based on stimulated Brillouin scattering in fiber amplifiers

Phase-conjugating stimulated Brillouin scattering (SBS) mirrors are frequently used to improve the brightness of solid-state lasers. With a scheme for designing fiber amplifiers as SBS phase conjugators the power requirements can be decreased by orders of magnitude; yet only low coherence is required, and high fidelity is reached. A peak power of 5 W was demonstrated to be sufficient for optical SBS phase conjugation.     

利用受激布里渊散射在光纤中实现光存储

利用有限差分法在慢变包络近似下求解了耦合波方程组,并从理论上实现了短光脉冲的存储。研究了数据脉冲的读出效率随声子寿命、布里渊增益系数、数据脉冲强度和控制脉冲强度的变化规律。结果显示:在长声子寿命的条件下,可以获得高的读出效率和长的存储时间,而布里渊增益系数和数据脉冲强度对读出效率没有影响;增大布里渊增益系数可以降低所需控制脉冲的强度。这种方法对短脉冲可以实现有效存储,而对长脉冲不能实现存储。     

利用受激布里渊散射在光纤中实现光存储

利用有限差分法在慢变包络近似下求解了耦合波方程组,并从理论上实现了短光脉冲的存储。研究了数据脉冲的读出效率随声子寿命、布里渊增益系数、数据脉冲强度和控制脉冲强度的变化规律。结果显示：在长声子寿命的条件下,可以获得高的读出效率和长的存储时间,而布里渊增益系数和数据脉冲强度对读出效率没有影响;增大布里渊增益系数可以降低所需控制脉冲的强度。这种方法对短脉冲可以实现有效存储,而对长脉冲不能实现存储。     

Research on stimulated Brillouin scattering suppression based on multi-frequency phase modulation

The method of generating equal-amplitude spectral lines by multi-frequency phase modulation is used in stimulated Brillouin scattering （SBS） suppression. The spectra of three, five, seven, and eleven equalamplitude spectral lines are obtained in experiment with flatnesses less than 0.3 dB. Theoretical research on SBS suppression shows that the threshold power after modulation is in reverse proportion to the maximum square of amplitude moduli of fundamental frequency and the nth harmonic wave. The threshold powers of three, five, seven, and eleven equal-amplitude spectral lines are improved by 5.21, 8.36, 9.39, and 10.76 dB, respectively.     

Theoretical investigation on the pumping effect of stimulated Brillouin scattering on stimulated Raman scattering in water

The pumping effect of stimulated Brillouin scattering on stimulated Raman scattering is investigated theoretically through the coupled wave equations of stimulated Brillouin scattering and stimulated Raman scattering. The numerical simulations are in agreement with the experimental results. They indicate that the backward stimulated Raman scattering is excited and amplified collectively by both pump laser and stimulated Brillouin scattering.     

水中受激拉曼散射的能量增强及受激布里渊散射的光学抑制

为提高液体介质中受激拉曼散射的输出能量,提出了通过温度调控来抑制受激布里渊散射的方法,设计了532 nm多纵模宽带脉冲激光泵浦的受激拉曼散射发生系统,测量了不同温度下水中前向受激拉曼散射及后向受激布里渊散射的输出能量,分析了水温、泵浦激光线宽及热散焦效应对受激拉曼散射输出能量影响的物理机制.实验结果表明:通过降低水温可实现对受激布里渊散射过程的有效抑制,同时减小热散焦效应带来的光束畸变,从而有效提高受激拉曼散射的输出能量.研究结果对液体介质中的受激拉曼散射多波长转换具有重要意义.     

横向受激布里渊散射的抑制

从非线性光学的耦合波理论出发,结合流体力学的连续性方程,建立了光学元件中窄带泵浦的横向受激布里渊散射的二维理论模型,并在此基础上,利用数值模拟考察泵浦光带宽增加对受激散射过程的影响。研究表明:在一定的条件下,当泵浦光带宽略大于布里渊线宽时,受激散射过程的Stokes增益将显著降低;带宽越大,Stokes增益降低得越多;当带宽大于20GHz时,可以抑制横向受激布里渊散射带来的不良影响。另外,当带宽一定时,调制频率的改变也会影响受激散射过程,可以通过数值模拟确定最佳的调制频率。     

横向受激布里渊散射的抑制

 从非线性光学的耦合波理论出发，结合流体力学的连续性方程，建立了光学元件中窄带泵浦的横向受激布里渊散射的二维理论模型，并在此基础上，利用数值模拟考察泵浦光带宽增加对受激散射过程的影响。研究表明:在一定的条件下，当泵浦光带宽略大于布里渊线宽时，受激散射过程的Stokes增益将显著降低；带宽越大，Stokes增益降低得越多；当带宽大于20GHz时，可以抑制横向受激布里渊散射带来的不良影响。另外，当带宽一定时，调制频率的改变也会影响受激散射过程，可以通过数值模拟确定最佳的调制频率。     

Tunable and reconfigurable photonic microwave filter based on stimulated Brillouin scattering

A high Q-factor photonic microwave filter showing tuning and reshaping capabilities and based on stimulated Brillouin scattering is demonstrated. The filter bandpass can be continuously tuned, changing the microwave oscillator used to generate the pump power, and the filter shape can be modified by modulating the microwave tone. A single bandpass over the microwave spectrum can be obtained by using single-sideband suppressed carrier modulation. Experimental results demonstrate the wide tuning range of the filter, its reshaping capability, and Q factor of 670.     

On the material response in stimulated Brillouin scattering

We re-examine behavior of the material response in stimulated Brillouin scattering and from this revise its theoretical formalism. We show that the response out of exact Brillouin resonance splits into two processes: one is the induction of a moving density grating, propagation characteristics of which follow these of the beat pattern of pump and Stokes fields, and the other is the induction of an acoustic wave, frequency of which coincides with that of the beat pattern but which propagates at the acoustic velocity in the medium. The resulting equations for the response amplitudes are solved analytically in several representative cases.