Sesam 1.06¦Ìm Laser Passively Mode-locked Picosecond Pulses Of A Single Measurement

In a long time,people always use organic dye as the component of psssive Q-switching or mode-locking in Nd3+ solid laser.But organic dye is poisonous and has a bad stability,which used discommodious. Recently,the Cr4+:YAG crystal has good performance in Q-switching,but has a bad performance in mode-locking:longer duration, bad stability and so on. For the advantages of simple constructure,good stability,narrow duration and good beam quality, SESAM has been used in CW Nd:YVO4 or Nd:YAG laser for passive mode-locking.Firstly,by using the SESAM from Institute of Semiconductors,The Chinese Academy of Sciences, stable passive mode-locking operation was realized in a flashlamp pumped Nd:YAG laser.The experimental results showed that for the cavity length was 140cm,the pulse duration was 43.6ps,and the pulse train energy was 24mJ.The effects of cavity length and cavity constructure to the mode-locking were also studied experimentally. In addition, we analyzed the constructure of 1.06μm SESAM and the theory of passively mode-locking in theory.We also simulated the reflection spectrum of different pairs of DBR in SESAM and the distribution of electric field in DBR.Secondly,the nc-Si-SiNx film has saturable absorbed character to 1.06μm laser,we first found that it could be used in Nd:YAG laser for 1.06μm wavelength mode-locking.The duration of mode-locking was 32ps.When the film was inserted into a LD pumped CW Nd:YVO4 laser,high repetition passive Q-switching operation was obtained. The theory of passive Q-switching and mode-locking of the film was also explained reasonably by using the Two-Photon Absorption Mode. Lastly,for the problems of Second Harmonic Autocorrelator Measurement for ps pulse duration,which have mechanical error and reading error when scaning the moving arm and used very discommodiously for flashlamp pumped mode-locked laser, we described the second harmonic autocorrelator for single-shot measurement which can obtain the results one time . This measurement takes advantages of higher precision and easy operation.The theory of this method was analyzed and the setup also be constructed to measure pulse duration of ps laser.