Enhanced Q-switched distributed feedback fiber laser based on acoustic pulses

An acoustically Q-switched distributed feedback fiber laser with enhanced performance is presented. It is based on an FBG written in an erbium doped fiber, in which a dynamic defect is introduced by means of a short acoustic pulse. The performance of the laser depends on the reflectivity of the grating. In this work, we present two different Q-switched distributed feedback fiber lasers realized with active gratings of different reflectivities. Both lasers are characterized at different pump powers and repetition rates. It is shown that the performance of the laser based on the weaker grating was significantly improved with respect to the laser based on the stronger grating. In terms of peak power, the improvement was a factor of two. The average power was also improved. For example, at 50 kHz, it was increased from 280 μW up to 500 μW. In addition, we studied the performance of the laser when an electric square signal was used to drive the transducer, obtaining similar results to the case when a harmonic electric pulse was used.