We explored the dynamics of frequency-modulated (FM) pulses in a cascaded fiber configuration comprising one active and one passive optical fiber with multiple fiber Bragg gratings (FBGs) of different periods inscribed over the fiber configuration length. We present a theoretical formalism to describe the mechanisms of the FM pulse amplification and pulse compression in such fiber cascades resulting in peak powers up to ~0.7 MW. In combination with the decreasing dispersion fibers, the considered cascade configuration enables pico- and sub-picosecond pulse trains with a sub-terahertz repetition rate and sub-kW peak power generated directly from the continuous optical signal.
