Characterization of a fiber laser system for materials processing

Abstract

The physical parameters of the emission of a commercial Q-switched, Yb doped, 20 W fiber laser were measured and analysed under different operating conditions. The laser showed a gaussian profile, and its diameter and peak power coincided with the specifications, but the maximum beam power and pulse energies were 16% lower. The beam power correlated linearly with the pump power. The pulse energy increases with the pulse length for 2 and 20 kHz repetition rates but a ceiling of 80 μJ is attained for 200 kHz. The time needed to attain the maximum population inversion is about 50 μs. The time shape of the pulses is strongly dependent on the pulse length and changes significantly when going from 2 and 20 kHz to 200 kHz, probably due to the low population inversion attained in the latter case