Simulation And Experimental Study Of Spectral And Mode Based On Dual-Frequency Neodymium-Doped Microchip Laser

The Neodymium-doped laser gain medium is particularly suitable for the working scene of a microchip laser due to its high conversion rate and excellent thermal properties.In various practical scenarios,the frequency difference of the dual-frequency microchip laser is one of the key parameters affecting the application.The parameters such as laser gain medium material,temperature and cavity length have an important influence on the frequency difference of the dual-frequency microchip laser.Based on that,a dual-frequency microchip laser with different parameters of Nd:Gd VO₄ and Nd:YVO₄ as the gain medium crystal is built,and the frequency difference temperature characteristics and mechanism are studied.Then for the Nd:YVO₄ dual-frequency microchip laser,and study its beam quality and mode characteristics.The general contents of the full text are as follows:?1?Explain the practical significance and application prospect of the microchip laser,and then summarize the research status and development trend of the microchip laser at home and abroad.Finally,the structure of the paper is introduced.?2?Firstly,the basic principle of the laser is briefly described,and the laser Neodymium-doped gain medium parameters and optical cavity involved in this experiment are introduced.Then,because this experiment is a Neodymium-doped dual-frequency microchip laser experiment,the longitudinal mode frequency selection,the rate equations of the four-level system and the mode competition are analyzed.Finally,the oscillation threshold and output power are deduced.Then the basic formulas of single-pass photon loss and Gaussian beam in the cavity are deduced.?3?The frequency difference temperature characteristics of Nd:Gd VO₄ and Nd:YVO₄ dual-frequency microchip lasers with different parameters were studied.Firstly,the influence of crystal temperature control temperature on the frequency difference in Neodymium-doped dual-frequency microchip lasers with different cavity lengths is explored.The experimental results show that the frequency difference of the Nd:YVO₄ dual-frequency microchip laser with cavity lengths of 0.5 mm,0.8 mm and 1 mm varies with the crystal temperature control temperature of 0.34 GHz/?,0.12 GHz/?,and 0.044 GHz/?,respectively.The frequency difference between the Nd:YVO₄ and Nd:Gd VO₄ dual-frequency microchip lasers with the same cavity length is similar to that of the crystal temperature.The results show that for dual-frequency microchip lasers with different cavity lengths and different materials,it is found that the crystal temperature control temperature is positively correlated with the frequency difference of the dual-frequency signals.And the smaller the cavity length,the greater the effect of temperature on the frequency difference.Then the above problems are simulated from the perspective of the temperature characteristics of the crystal gain coefficient curve.The simulation and experimental results are in good agreement.The results show that for a dual-frequency microchip laser with different gain dielectric materials of the same cavity length,the larger the change of spectral width ?v with temperature,the greater the slope of the frequency difference of the dual-frequency signal with temperature.?4?The Nd:YVO₄ dual-frequency microchip laser with a cavity length of 1 mm was used to measure the light intensity distribution,and its beam quality was calculated and analyzed,and its mode characteristics were studied.Firstly,the light intensity distribution maps of Nd:YVO₄ dual-frequency microchip lasers were collected by beam analyzer and analyzed,and the beam waist width and far field scattering angle were calculated.The beam quality of the Nd:YVO₄?1 mm?dual-frequency microchip laser was calculated by the calculation formula of M² and the results were analyzed.It is calculated that M² in the X-axis direction is 3.06,M² in the Y-axis direction is 4.30,and the average beam quality factor M² is 3.73,and the beam quality is good.Then,the light intensity distribution map of the pumping light is collected and analyzed by a beam analyzer.Finally,the formation process of the self-reproducing mode is simulated by using the iterative principle of the parallel plane cavity mode and the pumping light experimental data.The simulation of the simulated pumping light in the plane cavity is analyzed and compared with the experimental data.The results show that this is a high-order mode laser.