| Optically pumped vertical-external-cavity surface emitting semiconductor lasers (OPS-VECSELs) is a novel all solid state laser, which with semiconductor gain structure material to be laser material.To be an outstanding member in laser family, OPS-VECSELs combined the manufacture structure of the diode pumped solid state laser and the traditional electrically pumped vertical-cavity surface emitting semiconductor lasers (EPS-VCSELs), and possessed high power, high conversion efficiency, good beam quality, wide range of tunable wavelength, etc. Today, OPS-VECSELs is widely used in many fields for its prominent advantages, such as high speed laser printing, optical data storage, laser communication, target detection, criminal investigation, biochemistry and material analysis, clinical medical, image display, etc.The emergence and development process of OPS-VECSELs is reviewed in the paper at first, then the basic principle and typical structure of OPS-VECSELs are introduced in detail. The semiconductor material system of VECSEL chip is elaborated systematically, and the gain material of the design theory and design process of VECSEL chip is studied deeply. The epitaxial growth and the packaging preparation technology process of VECSEL chip is studied based on the structure designed of VECSEL chip and the working characteristics of OPS-VECSELs. The thermal characteristics of OPS-VECSELs is studied deeply via finite element method, the theoretical model of OPS-VECSELs is set up based on the rate equation theory, the cavity structure of OPS-VECSELs is analyzed. Finally, a series of OPS-VECSELs experiments are carried out.The lattice mismatched between the two adjacent layer, the thickness weighted and the zero-stress method of strain balance are introduced based on the semiconductor energy band theory. The traditional structure of VECSEL chip is introduced, and each layer in the chip is designed one after another. The equations of Bragg reflector’s reflectivity and band width are set up based on the theory of multiple-beam interference and optical matrix, the influence of the number of Bragg layer and the refractivity difference of two materials on Bragg reflector’s reflectivity are analyzed.808nm and980nm double band mirror is designed based on the pattern of ((HL)DH)N, the reflectivity of99.991%and9.959%are obtained respectively. The influence of Indium composition in the InGaAs quantum well layer, P composition in the GaAsP and the width of InGaAs quantum well layer on laser wavelength are studied respectively. The method of multiple InGaAs strain quantum wells compensated symmetrically by GaAsP in double side of InGaAs layer is presented based on model solid theory, k.p theory, Pikus-Bir theory and standing wave condition, and the structure of980nm VECSEL wafer with13RPG InGaAs is designed. The preparation process of VECSEL wafer is given out. and the980nm VECSEL wafer is grown on GaAs substrate by Molecular Beam Epitaxy (MBE). The wafer’s characteristic parameters are measured, and the result show that the VECSEL wafer designed is very good. The GaAs substrate in the VECSEL wafer is removed by mechanical polishing and chemical etching, then the metallization on Surface of VECSEL chip and heat spreader, the heat spreader or VECSEL chip is welded to the heatsink via Indium solder at higher temperature. The heat spreader is bonded to the VECSELchip via liquid capillary bonding at last.The thermal model is set up based on the mechanism of waste heat generated in the OPS-VECSELs. The theory model of OPS-VECSELs is set up based on the rate equation theory, the laser threshold condition and the characteristics of output power are given out. then the numerical simulation is carried out. The cavity model of OPS-VECSELs is set up based on the equivalent resonator method, then the curves that the spot size of fundamental mode in the VECSEL chip and on the output mirror changes as the distance of laser cavity are given out in the paper. The equation of thermal load distribution in the active layer of VECSEL chip with DBM is set up firstly, the thermal characteristics of VECSEL chip with DBR and DBM are analyzed comparatively at the condition of same reflectivity and same thickness. The result show that thermal characteristics of VECSEL chip with DBM is better than VECSEL chip with DBR clearly.In order to study the influence of the difference chip packaging way to the thermal characteristics of VECSEL chip, VECSEL chip with double side bonding heat spreader is presented in the paper. The thermal characteristics of VECSEL chip with double side bonding heat spreader is studied theoretically and experimentally. The results show that the thermal characteristics of VECSEL chip is improved clearly. A series experiments of OPS-VECSELs are carried out at the different incidence of pump light, the different thermal management way and the different working temperature of VECSEL chip,4.6W978nm OPS-VECSELs is obtained and the max optical-to-optical conversion efficiency is29.7%at10℃.In order to study the influence of different pump beam distribution to thermal management of OPS-VECSELs. Annular beam is introduced into the laser pumping field firstly, and the influence of annular beam’s parameters on the thermal characteristics of OPS-VECSELs are analyzed via finite element method deeply.Then the experiment of annular beam pumped VECSELs is carried out, and4.64W978nm OPS-VECSELs is obtained at room temperature. At the same operating conditions, compared to VECSELs pumped by Gaussian beam, annular beam pumped VECSELs poccessed higher threshold, good thermal effect, permitting higher efficient pump power, and higher maximum output power. At last, the acousto-optical q switched OPS-VECSELs and the double frequency intracavity experiment are also shown in the paper,0.61W and0.86W489nm laser are obtained in CW and QCW laser cavity respectively. |
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