Actively Q-switched fiber ring laser employing a locally phase-shifted chirped grating

In this paper, a technique to change the grating phase-shift dynamically is incorporated to the ring laser scheme with single-longitudinal scheme (where the phase-shift is permanent). This increases the versatility of the laser significantly, since it can work either in a wavelength-tunable cw regime or in a Q-switched pulsed regime, adding pulsed light-based applications (as OTDR, or microprocessing of materials) to the list of potential uses of this type of narrow linewidth laser source.