Study on Tunable Long-Period Fiber Gratings Produced by Mechanical Method

A method to produce tunable long-period fiber gratings (LPFGs) based on the mechanical deformation is studied. The factors influencing the tunable LPFGs with jacket and without jacket are further analyzed. It is found that the tuning rate of resonant wavelength is about 17.7 nm/0.01 mm. When the pressure is below a threshold value, the loss peak increases with the increase of pressure, and can be tuned by about 16 dB. If the pressure exceeds a certain point, the loss peak will decrease. The additional loss increases with the increase of pressures. And under the fixed pressure, the loss peak decreases when the period number of grooved plate increases. To achieve the same loss peak, the pressure applied on the unjacketed fiber is smaller than that on the jacketed fiber. The experiment results will facilitate the application of LPFG to achieve gain flattening in EDFA and filtering.