Spectral Characteristics of Mechanically Induced Long-Period Fibre Gratings by New Double-Layer Grating Templates

We design a new double-layer grating template, which has the advantages of period uniformity, period number adjustability and continuous period regulation. By studying the transmission spectrum under the new template, we also find some new characteristics different from traditional fibre gratings: the resonant wavelength is mainly determined by the grating period; the intensity of transmission peak loss lies in the external pressures; the bandwidth of transmission spectrum can be controlled by the period number. Therefore, various applications can be realized by optimizing the transmission spectrum by reasonably selecting the matched parameters.