Light reflection from a Bragg grating during continuum generation

In this paper, the light reflected from a Bragg grating when a highly nonlinear pulse propagates through the grating, generating a continuum is measured. The authors found that the nonlinear processes generating the continuum are enhanced near the bandgap edges in both the forward and backward directions. The spectrum of the nonlinear FBG reflection is thus significantly different from the linear reflection spectrum in which light is only reflected within the bandgap. An amplified, modelocked Er-doped fiber laser (~35 fs pulses, average power of ~0.1 W) was spliced to a length of OFS highly nonlinear fiber (HNLF) containing a Bragg grating resonance near 990 nm. The reflection was measured by inserting a ~0.25% tap into the standard single mode compressor fiber (SSMF).