Pulsed Laser Output Characteristics Regulation Based On Metal Oxide Saturable Absorber

Pulsed lasers have deep applications in laser processing,biomedicine,and optical communication due to their advantages such as high peak power and pulse energy.The realization of pulsed laser can be divided into active modulation and passive modulation.The passive modulation method based on real saturable absorbers has the advantages of compact structure and stable operation,and has become an effective way to generate pulsed lasers.Therefore,the search for high-quality saturable absorbers has a decisive impact on the development of pulsed lasers.During the exploration of saturable absorbers,metal oxides have attracted a lot of attention due to their advantages such as low cost,strong environmental stability,high damage threshold and good light absorption.With the progress of technology,people put forward more and more demanding requirements for pulsed lasers,which are developing toward large pulse energies and high peak powers.Currently,the output pulse energy and peak power of passively Q-switched fiber lasers based on saturable absorbers（SA）are low,so it is extremely important to regulate their output characteristics.In this paper,the output characteristics of the Q-switched laser are tuned by using some metal oxides as SA to enhance the peak power and pulse energy by anti-saturation absorption and increasing the damage threshold,respectively,it provides a new research direction and development idea for the development of high power and high energy pulsed laser..The main elements are as follows.1.The saturable absorption characteristics of Fe₃O₄nanoparticles-polyimide（PI）films（with different concentration ratio）in the near-infrared band were investigated,and stable Q-switched laser output was achieved using them as SA.Fe₃O₄nanoparticles were prepared by hydrothermal method and Fe₃O₄nanoparticles-PI thin films were prepared.Finally,optimization of the Q-switched laser output characteristics was successfully achieved in Er-doped fiber laser using Fe₃O₄nanoparticles-PI films（1:5）,the simultaneous compression of pulse width and repetition frequency has been realized for the first time,and the single-pulse energy and peak power were boosted to 364 n J and 554 m W.2.The saturable absorption characteristics of Cu Cr O₂nanoparticle-PI films in the near-infrared band were investigated,and a Q-switched laser output was achieved by using them as SA.Cu Cr O₂nanoparticles were prepared by hydrothermal method,and Cu Cr O₂nanoparticles-PI thin films were prepared.They were used as saturable absorbers to optimize the output characteristics of Q-switched lasers in Er-doped and Yb-doped fiber laser,respectively,the pulse width and repetition frequency are simultaneously compressed by an order of magnitude.In the Yb-doped fiber laser,the single pulse energy and peak power were increased to 283.6 n J and 1997 m W,and in the Er-doped fiber laser,the single pulse energy and peak power were increased to 242.1 n J and 2397.8 m W.3.The saturable absorption properties of Cu Fe O₂microcrystals in the near-infrared region and their applications in lasers were investigated.Cu Fe O₂microcrystals were prepared with the help of hydrothermal method and prepared as film devices.It was used as a new SA to realize the Q-switched pulse output.In addition,Si O₂colloids were prepared by the sol-gel method,and Cu Fe O₂microcrystals were plasticized in them to prepare SA with high damage resistance threshold.Based on this,a high power Q-switched laser output is realized,with the maximum output power up to 59.6 m W,single pulse energy and peak power up to 307.7 n J and 723.98 m W.