Gain and noise characteristics of a Brillouin amplifier
Gain and noise characteristics of a Brillouin amplifier
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DOI：
10.1364/josab.7.000929
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发表时间：
1990-06
期刊：
影响因子：
--
通讯作者：
A. Scott;D. E. Watkins;P. Tapster
中科院分区：
文献类型：
--
作者：
A. Scott;D. E. Watkins;P. Tapster
研究了布里渊放大器用于放大微弱信号和用于相位共轭时的增益和噪声特性。该放大器由一个填充TiCl4的20厘米长的小室组成，该小室由近衍射限制注入种子的NdYAG光输出的25 ns脉冲泵浦。布里渊增益由G B=exp(GIPL)给出，其中Ip是输入泵浦强度；对于500fJ的信号，测量了超过109的增益。观测到的信噪比为85：1；在理论极限的16倍之内。在没有信号的情况下，观察到输出噪声的变化为Nout=N o G B/g，其中N o是等于输入噪声信号的自发散射项。当像差器放置在光束前面时，与泵浦光束共轭的噪声强度增加了J>；2倍，即Nout PC=N o G J/J G。增强因子依赖于泵浦光束中的散斑，J>；3的观测值比理论预测的要大。
We have studied the gain and noise characteristics of a Brillouin amplifier, both when it is used to amplify weak signals and when it is used for phase conjugation. The amplifier consists of a 20-cm long cell filled with TiCl4 which is pumped by a 25-ns pulse from a near diffraction-limited injection seeded Nd:YAG laser. The Brillouin gain is given by G B = exp(gIpL), where I p is the input pump intensity; and gains in excess of 109 have been measured for signals of 500 fJ. The observed signal-to-noise ratio is 85:1; within a factor of 16 of the theoretical limit. In the absence of a signal, the output noise is observed to vary as Nout = N o G B /g, where N o is a spontaneous scattering term equivalent to an input noise signal. When an aberrator is placed in front of the beam, the intensity of noise which is conjugate to the pump beam is enhanced by a factor J > 2, i.e., Nout pc = N o G J /Jg. The enhancement factor depends on the speckle in the pump beam, and observed values of J > 3 are larger than predicted by theory.