Broadband edge filter based on a helical long-period fiber grating and its application to a power-interrogated torsion sensor

A broadband edge filter with linear dynamic ranges of 40 nm in wavelength and 93% in transmission loss has been demonstrated both theoretically and experimentally, which is achieved by using a helical long-period fiber grating (HLPG) operating near the dispersion turning point (DTP) of the LP1,10 mode. To take full advantage of the wide dynamic ranges, the fabricated edge filter has been successfully used as a power-interrogated torsion sensor, and the torsion responsivity presented is about 0.501 nm/(rad/m), which is higher than most conventional HLPG-based torsion sensors. The results indicate that the proposed edge filter may find applications in any other kinds of power-interrogated sensors as well. (C) 2022 Optica Publishing Group