Phase-shifted moiré grating fibre resonators

Bandpass transmission filters based on phase shifted fiber Bragg gratings in microstructured polymer optical fibers

“…The phase-shifted structure can also be reproduced as a Moiré grating where two gratings of equal amplitude but different periods, Λ and Λ , are superimposed [34]. This structure has one rapidly, Λ , and one slowly, Λ ,varying envelope, as shown in Figure 3.…”

“…Then, a second grating was written over the same length of the fiber in the second step of the fabrication process. Therefore, both gratings were spatially superimposed leading to a Moiré grating which exhibits a phase shift at the central point [34]. Other examples of dual FBG inscription can be found in the literature, such as spatially close [37] or spatially overlapped [38] polymer FBGs with different Bragg wavelengths.…”

“…In this paper, to the best of our knowledge, we report on the fabrication of FBG with one or more phase shifts in polymer fibers by using the phase mask technique. Two gratings with slight different periods have been superimposed in the fiber in order to form a Moiré structure with a π phase shift in the center of the device [34][35]. Simulations have been done to predict the response of the fabricated structures and very narrowband transmission filters are fabricated.…”

Design of Photonic Band Gap Filter

“…Another class of most popular filter based on the phenomenon of multi-beam interference and based on waveguides [34][35][36][37].…”

Complex Bragg grating writing using direct modulation of the optical fiber with flexural waves

“…3(b)-which is expected from the from the Fourier transform of the superperiod. 12 For the case when the modulation is continuous, the period tends to zero, and a sync-sampled fiber grating 13 with a phase-shifted spectrum (similar to a phase-shifted Moiré grating 14 ) is generated, as shown in Fig. 4.…”