An efficient 0.04-nm apodized fiber Bragg grating and its application to narrow-band spectral filtering

A narrow-band apodized fiber Bragg grating was fabricated with a phase mask method that incorporated a fluorescence monitoring technique, The grating length was 100 mm and the 3-dB reduced bandwidth was as small as 0.04 nm, The 20-dB reduced bandwidth was 0.1 nm at a center wavelength of 1554 nm, A single longitudinal oscillation mode of a 10-GHz pulse train from a mode-locked fiber laser was successfully extracted using the grating.