| Passively Q-switched solid-state lasers are widely used in bio-medicine,remote sensing,scientific research and other fields because of their simple structure,low price,high peak power and high single pulse energy.The saturable absorber is the most important component in the passively Q-switched solid-state laser.Cr:YAG crystal has the advantages of high stability and reliability,long service life,simple use and high damage threshold.It is an ideal passive Q switch used in micro lasers on the market.In addition,with the development of science and technology,some new wide-band saturable absorbers with nonlinear optical response have come into the field of scientific research,and have been used in passively Q-switched solid-state lasers.These new materials have lower preparation cost and simpler preparation process.They are a good Q switch in high-performance passively Q-switched solid-state lasers,and are also a new direction in the field of scientific research.In this article,we mainly study the physical and optical properties of two kinds of saturable absorbers,Cr:YAG crystal and WS2 nanomaterial,and apply these two kinds of saturable absorbers as Q switch in solid-state lasers to obtain high performance pulsed laser output.In addition,an integrated prototype of passively Q-switched solid-state laser based on Cr:YAG crystal is also made.The specific content of this article is as follows:1.Firstly,the physical and optical properties of two kinds of saturable absorbers,Cr:YGA crystal and WS2 nanomaterial,are introduced.Then,based on the output relaxation oscillation of pulsed solid-state laser,the basic principle of Q-switched technique is introduced.Finally,the process of derivation and solution of the rate equation is given.2.The effects of initial transmittance of Cr:YAG,cavity length and OC reflectivity on the output pulse laser parameters were experimentally studied.According to the experimental results,a separate crystal passively Q-switched solid-state laser was designed and built,and a pulse duration of 696 ps,single pulse energy of 563 ?J,peak power of 809 kW passively Q-switched laser was obtained.3.Nd:YAG/Cr:YAG bonded coated crystals were used as experimental objects.The output laser pulse duration is as narrow as 550 ps,the corresponding pulse energy is 120 ?J,the peak power is 217 kW.Next,Nd:YAG/Cr:YAG bonded coated crystal is excited by a continuous light source,and the pulse duration of output laser is relatively wide,which is 745 ps.The corresponding average output power is 492 mW and the repetition rate is 3.1 kHz.In contrast,it is easier to obtain the Q-switched pulse laser with narrow pulse duration than that pumped by continuous light source because of the better heat dissipation effect of the pumped bonded crystal by pulsed light source.4.A 532 nm Cr:YAG passively Q-switched solid-state laser prototype is designed and integrated.The size of the prototype is 71×34×27 mm3,the output laser pulse duration is 485 ps,the single pulse energy is 20?J,and the peak power is 41 kW.The laser has the advantages of small size,compact structure,good beam quality and stable performance.5.Using ethyl orthosilicate,water,hydrochloric acid,alcohol and WS2 aqueous solution as raw materials,WS2 saturable absorber was prepared by sol-gel method.SEM,EDS,LRS and other equipment were used to analyze and characterize the saturable absorber,which indicated that we successfully prepared several layers of WS2 saturable absorber protected by gel SiO2.The prepared saturable absorber was applied to Nd:YVO4 laser,and a pulse laser with average output power of 3.09 W and pulse duration of 99 ns was obtained.This work shows that sol-gel technology has great potential for preparing high performance saturable absorbers,which can greatly improve the laser performance parameters. |
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