Improvement on peak-to-trough ratio of sampled fiber Bragg gratings with multiple phase shifts

Via a cascaded structure, the peak-to-trough ratio is considerably improved for sampled fiber Bragg gratings （SFBGs） based on multiple-phase-shift （MPS） technique. This cascaded filter is composed of two identical SFBGs which are inserted with the increasing or decreasing arrangement of phase shifts. With this inverse arrangement of MPS in grating design, the phase fluctuation of individual SFBG can be compensated, and as a result an excellent phase matching condition is realized. In this way, the peak-to- trough ratio in reflection spectra is improved from 6 to 12 dB when multiplication factor m = 4, and from 5dBto 10dBwhenm=8.     

Improvement on peak-to-trough ratio of sampled fiber Bragg gratings with multiple phase shifts

Via a cascaded structure,the peak-to-trough ratio is considerably improved for sampled fiber Bragg gratings(SFBGs)based on multiple-phase-shift(MPS)technique.This cascaded filter is composed of two identical SFBGs which are inserted with the increasing or decreasing arrangement of phase shifts. With this inverse arrangement of MPS in grating design,the phase fluctuation of individual SFBG can be compensated,and as a result an excellent phase matching condition is realized.In this way.the peak-to- trough ratio in reflection spectra is improved from 6 to 12 dB when multiplication factor m=4.and from 5 dB to 10 dB when m=8.