A new versatile patent-pending method to synthesize ultra-high (>2 GHz) repetition rate bursts of ultrashort laser pulses, overcoming many limitations encountered by other fiber-based techniques, is introduced in this work. The developed method was based on the use of an all-in-fiber active fiber loop which enabled to synthesize bursts of laser pulses with any desired pulse repetition rate (PRR) (even up to hundreds of GHz) which does not depend on the initial PRR of a fiber oscillator. Moreover, the bursts of ultrashort laser pulses containing any number of pulses in a burst (from 2 pulses to thousands of pulses inside the burst) with identical intra-burst pulse separation were demonstrated. Therefore, short and arbitrarily long bursts up to a few hundred nanosecond widths were synthesized using this method along with an additional temporal modulation of the initial pulse train. The amplitude of pulses within a burst was controlled by amplification conditions in the Yb-doped fiber providing a constant, decaying, or rising amplitude of the pulses within a burst as long as it was not limited by the effect of the gain saturation. A dispersion compensation mechanism was successfully implemented in the active fiber loop which allowed to obtain ultrashort pulse durations within the GHz bursts. The experimentally constructed high-power femtosecond (less than 350 fs) laser system operating in single-pulse and burst of pulses operation regimes, provided bursts of >2 GHz intra-burst PRR and output power of more than 25 W. This technology can pave a way for progress in science and improvement for industrial applications by building high-power femtosecond lasers with a unique set of parameters.