Characterization Of Diode-pumped Passively Continuous-wave Mode-locked Lasers With SESAM

Ultrafast lasers with ultrashort pulse duration, high pulse repetition rate, broad spectrum and high peak intensity are attracting growing interest because of numerous applications in physics, biology, laser spectroscopy, optical communications and laser precision processing, nonlinear frequency conversion etc. Since the invention of semiconductor saturable absorber mirrors (SESAM) in 1992, the passively mode-locked lasers with SESAM have developed rapidly over the past decade because of their many virtues such as robust, inexpensive, compact etc. In this dissertation, we discussed the technologies of continuous operation of fundamental and second harmonic generation, as well as mode-locking laser properties in diode-pumped Nd:YVO₄/Nd:GdVO₄ solid-state lasers. The contents can be outlined as below:1. Review of the history and development of all-solid-state pulses lasers. The main approaches and new results of all-solid-state pulses laser at present are summarized.2. Based on the mode-locking principle and mechanism, the process of passive mode-locking by SESAM is described. And discussed the stability criterion of achieving cw mode-locking derived from rate equations.3. We experimental studied on LD pumped Nd:YVO₄/SESAM passively mode locking lasers used Z-cavity and W-cavity. 2.81 W Q-switched mode-locking laser output in the 1064nm is obtained corresponding to pump power of 7.5W in the Z- cavity; the optical-optical efficiency reached 37.5%. In the W-cavity, the threshold for continuous-wave mode-locked is relatively low, about 2.15W at the incident power of 6.65W. The repetition rate was 105MHz, and the pulse width was about 15ps.4. Experimental studied on LD pumped Nd:YVO₄/SESAM passively mode locking lasers, and obtained low threshold cw mode-locking operation. The maximum output power was 2.04W at the incident power of 6.65W, and the slope efficiency reached 33%, and the pulse width was about 10.5ps.5. The theory of the second harmonic generation is introduced simply. A laser-diode-pumped passively mode-locked Nd3+:YVO₄/KTP and Nd3+:GdVO₄/KTP green laser with a SESAM saturable absorber is explored. In the Nd:YVO₄ laser, 236mW mode-locking laser output in the second harmonic wavelength of 532 nm is obtained. In the Nd:GdVO₄ laser, 380mW mode-locking laser output in the second harmonic wavelength of 532 nm is obtained. So far as we know, this is the first report for green laser with SESAM saturable absorber.