伽马射线辐照增益光纤对光纤放大器低频噪声特性的影响

Investigation on Low Frequency Noise Characteristics of Fiber Amplifier Influenced by Gamma-Ray Irradiated Gain Fiber

针对光纤放大器的空间应用,对光纤放大器在辐射环境中的性能变化进行了实验研究。对铒镱共掺光纤放大器的增益光纤进行伽马射线辐射,研究了光纤放大器的输出功率和光谱特性的演化规律,并采用频谱测量法研究了光纤放大器的噪声特性。通过总剂量为50 krad的在线辐照实验发现,光纤放大器输出功率、光谱的中心波长峰值功率以及光噪声都随着辐射剂量的积累而不断降低。采用光噪声模型对辐射后的光纤放大器噪声特性进行分析,与辐射前相比,发现光噪声中的弛豫振荡噪声部分和中频部分的相对强度噪声系数分别增加了1.625×10-4 nW·mW-2·Hz-1和3.122×10-4 pW·mW-2·Hz-1,而光散粒噪声系数分别减小0.900 pW·mW-1·Hz-1和0.035 pW·mW-1·Hz-1,对于光纤放大器在太空的实际应用中,需要重视相对强度噪声的抑制。

For the space applications of fiber amplifier,the radiation performance of fiber amplifier in radiation environment was investigated experimentally.The evolution laws of output power and spectral character are investigated experimentally by irradiating the gain fiber of an erbium-ytterbium co-doped fiber amplifier with gamma rays.The investigation of the noise characteristics of erbium-ytterbium co-doped fiber amplifier has been carried out by means of frequency spectrum measurement.In the on-line irradiation experiments,with a total radiation dose of 50 krad,it is found that the laser output power,the power of peak wavelength and optical noise decrease with the increment of radiation dose.The noise characteristics of the fiber amplifier are analyzed by the optical noise model after irradiation.Compared with the results before irradiation,the coefficients of relative intensity noise of relaxation oscillation noise and the intermediate frequency part are increased by 1.625×10-4 nW·mW-2·Hz-1 and 3.122×10-4 pW·mW-2·Hz-1,respectively,while the coefficients of shot noise are reduced by 0.900 pW·mW-1·Hz-1 and 0.035 pW·mW-1·Hz-1,respectively.Therefore,it is necessary to pay attention to the suppression of the relative intensity noise for the practical application of fiber amplifier in space.