基于弯曲不敏感光纤的长周期光纤光栅可调谐增益均衡器

对高频CO2激光脉冲方法在弯曲不敏感光纤中写入的长周期光纤光栅的弯曲特性进行了研究，发现其谐振峰幅值对弯曲相当敏感，为普通光纤中写入的长周期光纤光栅的2．8倍，并且谐振波长和谐振峰幅值在圆周方向上呈现的对应规律与普通光纤不同．即谐振峰幅值最敏感方向所对应的谐振波长对弯曲不敏感。根据该现象，提出了一种利用调节其弯曲度来实现增益控制的可调增益均衡器方案，并进行了实验验证，该方法实用、简单。

A Novel Tunable LPFG Gain Equalizer Based on a Bend Insensitive Fiber

Thebending characteristics of the long period fiber grating (LPFG) induced by high-frequency CO 2 laser pulses in a bend insensitive fiber is reported. The experimental results show that the peak resonant amplitude of the LPFG written in a bend insensitive fiber has a higher sensitivity than that written in a standard telecommunication fiber. Furthermore, LPFG has different bending characteristics at circular orientation, i.e. the peak resonant amplitude of the LPFG is the most sensitive to bending but the resonant wavelength is insensitive at some circular orientations. Based on this finding, a gain equalizer is proposed to flat the gain of an erbium-doped fiber amplifier (EDFA) by bending directly. Such a system is shown to be a practical and simple approach to realize gain flattening of an EDFA with high precision for gain control.