Fig. 11: Reflection Spectra of FBGs with different linewidths.
From: Transverse mode coupling in monolithic few-mode fiber laser oscillators
a HR/LR with the 3-dB linewidth of 0.7/0.05 nm; b HR/LR with the 3-dB linewidth of 1.8/0.3 nm; c HR/LR with the 3-dB linewidth of 0.5 nm; d HR/LR with the 3-dB linewidth of 0.7 nm; e HR/LR with the 3-dB linewidth of 1.8/1.0 nm; f HR/LR with the 3-dB linewidth of 1.8/1.6 nm
