Group delay ripple of cascaded Bragg grating gain flattening filters

Chirped fiber Bragg gratings used as gain flattening filters were fabricated with peak-to-peak group delay ripple (GDR) less then 3 ps. It is shown that GDR of cascaded similar filters grows as the square root of their number. Group delay measurement is discussed and ripple quantifiers using peak-to-peak amplitude root-mean-square amplitude 100-pm window averaged amplitude and highest Fourier amplitude are compared. GDR of gain flattening filters based on chirped fiber Bragg gratings should not cause significant impairments in systems operating at 10 and 40 Gb/s.