Title :
Analysis and suppression of Q-switching instabilities in mode-locked lasers-a control systems approach
Author :
Grawert, Felix J. ; Kärtner, Franz X.
Author_Institution :
Dept. of Electr. Eng., Massachusetts Inst. of Technol., Cambridge, MA, USA
Abstract :
We investigate the origin of Q-switching instabilities in a mode-locked laser from a control systems viewpoint. The laser is represented as a linear control system, and we consider active laser stabilization either by gain or by loss control as well as passive stabilization via inverse saturable absorption. Gain control stabilization compensates for low-pass filtering in the gain relaxation branch of the system, while control of intracavity losses directly counteracts the destabilizing effect of the saturable absorber. For both stabilization approaches, design rules are derived for controller gain and bandwidth, and their applicability to different laser systems is investigated. Our discussion is concluded with a control systems analysis of passive laser stabilization via inverse saturable absorption. The control systems representation makes the established methods of control theory available to active and passive laser stabilization.
Keywords :
Q-switching; gain control; laser cavity resonators; laser mode locking; laser stability; low-pass filters; optical losses; optical saturable absorption; optical variables control; Q-switching instabilities; active laser stabilization; gain control; gain relaxation; inverse saturable absorption; linear control system; loss control; low-pass filtering; mode-locked lasers; passive stabilization; Absorption; Band pass filters; Control systems; Filtering; Gain control; Laser mode locking; Laser stability; Laser theory; Low pass filters; Optical control; Active and passive laser stabilization; control systems theory; laser dynamics; mode-locking;
Journal_Title :
Quantum Electronics, IEEE Journal of
DOI :
10.1109/JQE.2005.858795
