Passively mode-locked technology, utilized in generating laser pulses with ultrashort duration, high repetition rate and high peak intensity, has more applications in high-capacity telecommunication systems, nonlinear frequency conversion, laser spectroscopy, and optical coherence tomography(OCT) etc. By the year of 1992, the invention of Semiconductor Saturable Absorber Mirror (SESAM) brought a revolution in the passively mode-locked solid state laser. Passively mode-locked laser with SESAM have developed rapidly for its inexpensive, compact, self mode-locking, self starting, and so on.Based on the theory of SESAM mode-locking, a passively mode-locked Nd:YAG laser with SESAM was constructed, which realized continuous mode-locking of maximum average power of 4.7W. It is the highest record of the same kind lasers in China. The paper is summarized as follows:1. The progress is reviewed of mode-locked laser with SESAM, especially focused on the development of passively mode-locked Nd:YAG laser.2. With the optical characterization and structure of SESAM , the stability criterion of continuous wave mode-locking derived from rate equations is discussed. The principle and phenomenon of passively mode-locked laser with SESAM is described.3. The theory and experiment on the thermal effect is introduced. After measuring the thermal focal length of the LD side-pumped Nd:YAG laser module accurately , the compensation method is discussed.4. According to the principle of continuous mode-locking and the performance of the Nd:YAG laser module, Suitable SESAM has been chosen, Different kinds of laser cavities are designed and analyzed with the ABCD matrix.5. A SESAM continuous passively mode-locked Nd:YAG laser is constructed successfully. The power, beam quality and other performance of laser is measured. Finally, the damage on the SESAM and the improvement of the laser are discussed. |