Open AccessMechanisms of generation of multi-peak and mode-locked resembling pulses in Q-switched Yb-doped fiber lasers
Author(s) -
B.N. Upadhyaya,
U. Chakravarty,
A. Kuruvilla,
K. Thyagarajan,
M. R. Shenoy,
S. M. Oak
Publication year - 2007
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.15.011576
Subject(s) - optics , fiber laser , q switching , pulse (music) , laser , materials science , modulation (music) , pulse width modulation , mode locking , pulse shaping , pulse duration , bandwidth limited pulse , power (physics) , physics , ultrashort pulse , quantum mechanics , detector , acoustics
The output pulse characteristics of Q-switched Yb-doped fiber lasers have been investigated experimentally. It has been observed that for any typical modulation frequency, the pump power and the modulator OFF-time govern the shape of the output Q-switched pulse. At a fixed modulation frequency, with a fine adjustment of acousto-optic modulation window ON-time, pump power and cavity mirror position, it was possible to obtain modulation free single-peak pulse, multi-peak pulse, mode-locked resembling pulse and multi-pulse structured pulse shapes in a Q-switched fiber laser output. These observations have been analyzed and explained. Our investigations show that multi-peak pulse output is due to onset of nonlinear phenomena like SBS and SRS. Similarly, we have found that the mode-locked resembling periodically modulated output pulse shape is due to mode beating between the zeroeth order and the first order diffracted beams of the intra-cavity acousto-optic Q-switch.