在光敏性掺铒光纤上制作了45 mm长非对称相移结构光纤光栅, 构成前后向功率输出比大于100∶1的分布反馈光纤激光器.利用一定长度的掺铒光纤吸收有源相移光栅后的剩余泵浦光, 实现了对前向输出激光信号的放大, 并采用OptiSystem软件模拟了掺铒光纤长度与增益的关系.为了保持输出激光的窄线宽和低噪音特性, 利用布喇格波长与激光相同的光纤光栅和光纤环行器构成光窄带滤波器, 对放大后激光信号的ASE噪音进行滤除.研究表明: 所设计的激光器结构充分利用了泵浦光, 在300 mW的(980 nm)泵浦功率下获得了功率为32.5 mW, 线宽为11.5 kHz, 相对强度噪音为－87 dB/Hz的激光输出.

A distributed feedback (DFB) fiber laser with a ratio of backward to forward output power of 100∶1 was composed by a 45mm length asymmetrical phase-shifted fiber grating fabricated on erbium-doped photosensitive fiber. Forward output laser was amplified and population inversion was got by using a certain length of Nufern EDFL980-Hp erbium-doped fiber to absorb surplus pump power after the active phase-shifted fiber grating. Using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with narrow line-width and low noise, a narrow-band light filter consisted of a fiber grating with the same Bragg wavelength as the laser and an optical circulator was used to filter the ASE noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, and a fiber laser of 32.5 mW output power, 11.5 kHz line width, and －87 dB/Hz relative intensity noise (RIN) at 300 mW of 980 nm pump power was gave.