Study On The Laser Performance Of Nd:GYSGG Crystal

With the development of laser technology, All-solid-state lasers （Laser diode-pumped solid-state lasers） have become a hot area of laser research due to their manyadvantages, such as compact, efficient, stable and long lifetime et al. they have beenwidely used in the fields of industry, medical treatment, military and research.Nd:GYSGG is a new radiation-resistant laser crystal which has good physicalcharacteristics and the merit of much higher efficient segregation compared with themost famous garnet laser crystal Nd:YAG, which is one key factor for growing highquality, high Nd3+concentration and large size crystals. The research of lasercharacteristics on Nd:GYSGG is of great significance for science and radiationenvironments.The main contents and structure of this dissertation are as follows:1. The principle of the method of spectrum、the laser efficiency comparisonmethod and the threshold formula method have been introduced. The stimulatedemission cross section for the4F3/2�'4I11/2transition at1.06μm of an Nd:GYSGGcrystal is measured at room temperature by both the laser efficiency comparisonmethod and the threshold formula method, with their values of about1.59×10-19and1.50×10-¹⁹cm², respectively. The measured results accord well with each other.2. We demonstrate an efficient diode-end-pumped dual-wavelength Nd:GYSGGlaser. For continuous-wave operation, the maximum output power is10.1W with theabsorbed power of18.45W at808nm, corresponding to the conversion efficiency of55%and the slope efficiency of60%. As to A-O Q-switched operation, the maximumsingle pulse energy reach277μJ and the pulse width of is about60ns when theabsorbed pump power is11.4W.3. The operating characteristics of a Nd:GYSGG laser in the1.3μm wavelengthband based on the transition⁴F_3/2�'⁴I_13/2transition is demonstrated. Using a plane-parallel cavity and two different output couplers, single wavelengths operation at1336nm and dual-wavelength operation at1321/1336nm are obtained. The1329nmlaser spectrum is also found when the pump level is relatively weak. The stimulatedemission cross section of the1336nm laser line is estimated to be1.12time of that of the1321nm laser line. The output power of1.98W at1336nm is achieved with thepump power of13.5W, corresponding to the conversion efficiency of14.7%.4. A continuous-wave （cw）937nm Nd:GYSGG laser based on the quasi-three-level transition4F3/2�'4I9/2is reported. The output power of0.80W at937nm isachieved with the incident pump power of8.2W, corresponding to the conversionefficiency of9.8%and the slope efficiency of15.3%at T=0oC. The variation ofoutput power and pump threshold with increased working temperature is also studied,and we also simulate the three dimensional temperature fiels distribution ofNd:GYSGG crystal under different pump power and boundary temperature in theory.