Research On LD Pumped Acousto-optic Q-switched Laser Based On Nd:YAG Crystal

Since the appearance of LD pumped all-solid state laser in the late 1980 s,the laser technology has been changed dramatically.All-solid-state lasers are widely used in medical treatment,communication,printing,scientific research,material processing and military applications for their advantages of high output power,high pulse energy,ultrashort pulse width and good beam quality.The stability of work performance has become a research hotspot,which has promoted the development of traditional and emerging industries.In the present dissertation,we discussed the technologies of continuous wave operation of acousto-optic(AO)Q-switching laser properties in diode-side-pumped solid-state lasers.The main contents are as follows: 1.Review of the history and development of all solid state lasers,the application of Nd:YAG in lasers and the development of Q-switching lasers in recent years are briefly introduced.2.The requirements of diode solid-state laser medium are briefly described,and the solid laser medium used is analyzed.After detailed analysis of the characteristics of Nd:YAG,the physical properties and laser performance,optical properties,energy transition structure and spectral characteristics are given.Three kinds of pump type LD commonly used the advantages and disadvantages are described.3.Firstly,the basic principle of Q modulation is introduced briefly,and then the differences between active Q and passive Q and their main Q modulation types are explained.Finally,the principle of AO modulation and the AO Q modulation technology based on AO modulator are introduced in detail.4.In this paper,the Q-switched rate equations are studied in theory,and the fourth-order Runge-Kutta method is used to simulate them in detail.The numerical simulation of Q-switched equations are obtained.The effects of loss,cavity length,the initial photon number density and the initial inversion number density on the pulse waveform are obtained.The larger the loss,the longer the cavity length,the smaller the peak value of photon number density and the smaller the pulse width.The initial photon number density and the initial inversion population density increase,and the time to establish the rising edge of the pulse is shortened.When the initial photon number density increases,the peak value of photon number density does not change obviously,while the pulse width does not change.With the increase of initial inversion population density,the peak value of photon number density increases obviously,but the pulse width does not change.5.The static output light and the side pump Q-switching were carried out in a flat cavity.In static state,when the current is 21 A,the maximum output power is 60 W,the corresponding optical-optical conversion efficiency is 12.98%.The relationship between the leakage power and the right distance of the Q switch is measured when the Q switch is turned off.When the right distance is 5.00 mm,the minimum power leakage is about 6W.The variation of output power with Q frequency is measured under the condition that the Q switch is often out of light.