采用2个交错放置的具有π相移的周期性刻槽板对弯曲不敏感光纤径向施力，形成了机械写制π相移长周期光栅(LPGs)滤波器。实验研究了压力和子光栅个数对π相移光纤光栅的光谱影响以及光栅的偏振相关损耗(PDL)。结果表明：两侧阻带的传输损耗由施加在光纤上面的压力决定，子光栅的个数决定π相移光纤光栅的通带宽度，但不影响通带中心波长；对LP13耦合模，当π相移个数从1增加到9时，滤波器通带带宽由8.2 nm增加到53.8 nm。LP13包层模具有最大PDL，其值约为6.86 dB。该方法制作的π相移长周期光纤光栅(LPFG)具有可重构性，结构简单，易于操作，在光纤通信和传感领域具有潜在的应用价值。

The optical filter based on mechanically-induced π-phase-shifted Long-Period Gratings (LPGs) formed by pressing a bend-insensitive fiber from two sides with two identical periodically grooved plates are investigated. The influence of the sub-grating number and pressure on the spectrum characteristics of the π-phase-shifted LPG are investigated experimentally, together with the Polarization Dependent Loss(PDL). The results show that the depth of the two lateral rejection bands varies with the strength of pressure applied to the fiber; the pass-band width of the grating depends strongly on the number of the sub-grating, while the central wavelength of the pass-band is independent of it. For LP13 mode coupling, the pass band width varies from 8.2 nm to 53.8 nm when N increases from 2 to 9. A maximum PDL of about 6.86?dB for LP13 cladding mode is measured. It is believed that the mechanically-induced π-phase-shifted Long Period Fiber Gratings(LPFGs) with the merits of reconstructable, simple and easy operation have potential applications in fields of fiber-optic communications and fiber-optic sensing.