Resonator Design Based On Thermal Effect And The Reseach Of Q-switched Mode-locked By MWCNT

Since the invention of laser technology in1960s, it has impacted people`s lives andproduction in various areas. Because of it`s compact structures, high stability, longusing life, good beam quality, high efficiency, diode pumped all-solid-state laser(DPSSL) has became the focus of research and development. DPSSL lasers are widelyused in material processing, medical treatment, military weapons, space communicationmeasurement, and optical information processing and other aspects. Due to the use oflaser-diode instead of the traditional flash as the pump sourse, DPSSL technology hasmade a great breakthrough, which makes sure the increase of output power and effic-iency in the future.Now reseachers are putting their eyes on how to improve the laseroutput power and get high-quality laser beam ect. but the main obstacle of improvingthe quality of laser comes from the thermal effects of crystal. Therefore, the study of thethemrmal effect of the laser crystal, and the design of the cavity resonator based on theinfluence of thermal effect on cavity resonator are impormant aspects.In this paper, we analyzed the thermal effect theory, built a simple model of crystalwhich was based on the thermal effect, established the boundary conditions, simulatedthe temperature field of Nd:YVO4. We also analysed the optical path diffrence andthermal focal length when crystal was pumed by laser-diode. According to the variationof the thermal focal length, we designed the z-shape resonator. We also studied theQ-switch mode-locked by MWCNT.It`s main contents can be summed as follows:1.In chapter one, we reviewed briefly the history of the development of the laser,and introduce the classification of DPSSL, compared the diffrence betweenDPSSL and troditional laser, we also introduced the principles of Q-switchedand model-locked technology, and their advantages and disadvantages; theprinciple of renosate and the diffirence of several styles; and the principle oflaser crystal to produce thermal effects and the impact on laser.2.In chapter two, we introduced briefly the laser material such as the charactors ofNd:YAG and Nd:YVO4; and the charactors of MWCNT as Q-switched andmodel-locked component. 3.In chapter three, we described and nanlysed the cause of thermal in detail, whichinclude thermal stress effect, thermal lens effect, birefringence effect and howto reduce the influence caused by the thermal effect. Built thermal effect model,presented boundary conditions and it`s Poisson equations and used computer tosimulate the thermal effect.4.In chapter four, according to the focal lenth changes caused by thermal effect, wecolumned the conduction matrix, designed z-shaped cavity, and analyzed theperformance parameters of the resonator.5.In chapter five, we demonstrated the features of Nd:YAG\MWCNT diode-pum-ed passively Q-switched mode-locked laser. And then we researched the slopeefficiencies of the continuous wave and Q-switched mode-locking operation.Finally we studied the mode-locked pulse width changes with pump power.