Densification of sampled fiber Bragg gratings using multiple-phase-shift (MPS) technique

The authors recently proposed the multiple-phase-shift (MPS) technique, in which multiple phase shifts are introduced in sampled fiber Bragg gratings (SFBGs) to realize dense channel spacing. In this paper, the MPS technique is studied in detail, and it is shown that it can densify SFBGs both spectrally and spatially. Then, the paper presents that the MPS technique is applicable to densify the spectra of not only simple SFBGs but also various kinds of complex SFBGs, such as apodized, sinc-, and chirped SFBGs.