| Visible laser is a laser that can be perceived directly by human eyes.It has important applications in laser collimation,laser display,laser processing,laser communication and other fields.Pr3+:YLF crystal can provide many visible transitions such as blue light,green light,red light and deep red light.And the spectral lines have good continuity and tunability.Therefore,the Blue-LD pumped Pr3+:YLF visible solid-state laser has been widely concerned by researchers and has become a research hotspot in recent years.The peak wavelengths corresponding to the 3P0→3F3 transition of Pr3+:YLF crystal are 696 nm and 698 nm.Among them,the monochromatic laser at 696 nm can not only be used to improve the image resolution of trivalence chromium triaminomethane oxalate complex,but also plays an important role in the chlorophyll equation spectroscopic analysis of methanol and the enzymatic reaction step of photoinduced reduction of chlorophyllol ester.The monochromatic laser at 698 nm with narrow linewidth can be used to detect the frequency signal of the optical lattice clock of cesium atom,which is of great significance in the research of high precision atomic clock.In this thesis,we mainly study the 696 nm and 698 nm of the LD-pumped Pr3+:YLF visible solid laser.The main research work includes the following parts:(1)The absorption and emission spectra of Pr3+:YLF crystal with doping concentration of 0.5at%were measured and analyzed.At the same time,the film system of laser cavity mirror is designed and fabricated.In addition,the laser performance of Pr3+:YLF laser is analyzed theoretically.These works have laid a theoretical and experimental foundation for the subsequent experiments.(2)LD-pumped Pr3+:YLF laser at 698 nm was experimentally studied.Comparative experiments were carried out with focusing mirrors of 40 mm,50 mm and 75 mm respectively.The results show that the best matching effect and the best laser performance can be achieved when the pump light is concentrated into the laser crystal of 5 mm with a focusing mirror of 50 mm.Then,we use a flat-convex lens with a focal length of 50 mm as the focusing mirror,and use output mirrors with transmittance of 0.47%,1.37%and 1.88%respectively to carry out comparative experiments.When the transmittance of output mirror is 1.37%,the best performance of the laser is obtained.The maximum output power of 506 mW is obtained.The slope efficiency relative to the absorbed power is 29.1%.(3)LD-pumped Pr3+:YLF laser at 696 nm was experimentally studied.Firstly,the basic principle of frequency selection with F-P etalon is introduced.Then,based on the experiment of 698 nm laser,the F-P etalon is used to select the frequency,and the laser at 696 nm is obtained.Use output mirrors with transmittance of 0.49%,1.51%and 1.94%respectively to carry out comparative experiments.When the transmittance of output mirror is 0.49%,the best performance of the laser is obtained.The maximum output power of 258 mW is obtained.The slope efficiency relative to the absorbed power is 17.0%.This is the maximum output power that has been reported under Blue-LD pumped Pr3+:YLF laser at 696 nm.(4)A 349 nm UV frequency-doubling Pr3+:YLF laser pumped by blue LD has been experimentally studied.Firstly,the basic theory of frequency doubling is analyzed and introduced.Then,LD with maximum output power of 22.1W and peak wavelength of 444 nm is used as the pump source.A 3*3*15 mm3 Pr3+:YLF crystal with an doping concentration of 0.2%was used as the laser working crystal.A 4*4*7 mm3 BBO crystal with type Ⅰ phase matching and a crystal cutting Angle of 33.8° is used as a nonlinear frequency doubling crystal.Two plane mirrors and a concave mirror are used to form a V cavity.Finally,the maximum output power of 0.61 W at 349 nm is obtained.This is the maximum output power that has been reported under LD-pumped Pr3+:YLF UV frequency doubling laser at 349 nm. |
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