Research And Development Of Teaching Picosecond Pulse Laser

Mode-locking technology based on semiconductor saturable absorption mirrors（SESAM）has been applied in many fields such as scientific research and industry.By now,most of these products are imported from abroad,and the prices of the products are so high that they are usually used by scientific researchers.For this reason,an open picosecond laser based on SESAM mode-locked is developed,which is not only suitable for scientific research,but also can meet the needs of undergraduate and even graduate students in teaching and training.In our laser system a SESAM is used as mode-locked device,a 808 nm wavelength-locked semiconductor laser as pump source and a Nd:YVO₄ as gain medium.Through theoretical design and experiment,a mode-locked picosecond laser with ultra-low threshold is obtained,with continuous mode-locking output of 118mW at the pumping power of 1268mW.In order to further optimize the output characteristics of the laser,an autocorrelator is built to analyze the quality of the mode-locked output for the SESAM mode-locked laser.It is observed that the autocorrelation signal of laser pulse with parasitic oscillation contains multiple signal peaks.By placing the crystal angle at 8 degrees,and increasing 1 degree wedge angle of the rear end of the output mirror,the parasitic oscillation is suppressed.A SESAM mode-locked solid-state laser is designed with SOLIDWORKS software.The laser is divided into three zones,including the pump source,precision and open zones.The instrument can satisfy both scientific research and teaching needs.