Sensing and Demodulation of Special Long-Period Fiber Gratings Induced by Scanning Laser Pulses
Figure 20
(a) Transmission spectrum of the MZI. The separation of the two gratings was 33.0 mm and each grating consisted of 30 periods with a pitch of 435 μm. The gratings are fabricated in a twisted fiber with a twist period of 3.92 cm. (b) Lasing wavelength shift with torsion applied to the MZI. “−” means that the direction of the applied torsion is the same as that of the original torsion applied to the fiber [8].
