Abstract: Systems, methods, circuits and/or devices for generating high repetition rate ultra-short pulses are described. As one of many examples, an optical pulse generating laser system is described that produces mode-locked optical pulses. The laser system incorporates an optical pulse generation device that includes two optical loops coupled via a beam splitter. In addition, the optical pulse generation device includes an optical gain medium that is associated with the first optical loop, and a saturable element that is disposed in either the first optical loop or the second optical loop. The saturable element is operable to modulate a group of optical pulses propagating in at least one of the first optical loop and the second optical loop to create a group of substantially regular modulated pulses.