Modal interferometer based on tapering single-mode-multimode-single-mode fiber structure by hydrogen flame

A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-singlemode (SMS) fiber structure heated by hydrogen flame.The interference fringe begins to form when tapering length is 19.8 mm,and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller.Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5μm.The temperature and axial strain dependences of the tapered SMS structure are characterized,and the measured temperature and strain coefficients are +7 pm/℃and -9.536 pm/με, respectively.     

Theoretical analysis on double Rayleigh backscattering noise in optical fibreRaman amplifiers and its suppression

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fibre Raman amplifier is analysed. Expressions are presented for both forward pumping and backward pumping schemes. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The optimal position for the isolator is determined and is found to be insensitive to the power levels of the signals and pumps. The results show that a reduction of the DRB noise by almost 2 to 3 orders can be reached.     

喇曼放大器系统中光信噪比与传输码型相关性研究

分析研究了采用分布式光纤喇曼放大器的DWDM光纤传输系统中,瞬态泵浦消耗噪音对信号眼图、误码率等性能指标的影响,比较了不同比特率和信道数时这种噪音所带来的影响,给出了模拟仿真结果;分析并比较了瞬态泵浦消耗噪音与喇曼串扰噪音对系统性能影响的程度,同时分析了不同码型所对应的瞬态泵浦消耗噪音,发现归零码(RZ)具有更好的噪音特性.     

光纤拉曼放大器中双重瑞利背向散射噪声的抑制

研究了光纤拉曼放大器中双重瑞利散射噪声的特性，提出了在考虑拉曼光放大作用时，双重量早散射噪声的表达式。给出了在加入隔离器进入抑制后，双重量早散射噪声的计算方法，并进行了模拟分析，得出了旋转隔离器的最佳位置。