The thermal lens effect has emerged in recent years as a novel ,highly sensitive tool for the study of the very weak molecular absorption of light energy,This paper discusses the theory and technique of the thermal le...The thermal lens effect has emerged in recent years as a novel ,highly sensitive tool for the study of the very weak molecular absorption of light energy,This paper discusses the theory and technique of the thermal lens measurement.Some opplications of the thermal lens measurement are described.A mode-mismatched dual-beam thermal lens experimental arragement with a modulated probe beam ,designed by the authors.for trace analysis is presented,and its detection limit was found to be 4.1×10^-7 for Cu(Ⅱ) in ethanol and 80 mW excitation power.展开更多
In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive ...In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.展开更多
A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output pow...A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output power of 17.7 W is achieved by employing a 0.5 at.%doped sample,corresponding to an optical-to-optical efficiency of 46% with respect to the absorbed pump power.In addition,a numerical analysis and an experimental study of the temperature distribution,and thermal lens effect of the Nd:YVO4 thin disk,are presented considering the influence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor.The simulated results are in good agreement with the experimental results.展开更多
Diode-laser pumped monolithic single-frequency non-planar ring laser has the advantages of compactness, reliability and high efficiency. But when the pump power is high enough, the thermal effect will be serious and t...Diode-laser pumped monolithic single-frequency non-planar ring laser has the advantages of compactness, reliability and high efficiency. But when the pump power is high enough, the thermal effect will be serious and the high-order transverse modes will appear. Therefore the single-mode output power is limited. In this paper, the mechanism of generating the high-order transverse modes in the monolithic unidirectional non-planar ring cavity is analyzed using ray tracing method. The calculated results are in agreement with the experiments.展开更多
Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves （SAWs） are dispersive when the near-s...Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves （SAWs） are dispersive when the near-surface properties of materials are changed. So the near-surface properties （such as the thickness of hardened layers, elastic properties, residual stresses, etc.） can be analyzed by the phase velocity dispersion. To study the propagation of SAWs in metal samples after peening, a more reasonable experimental method of broadband excitation and reception is introduced. The ultrasonic signals are excited by laser and received by polyvinylindene fluoride （PVDF） transducer. The SAW signals in aluminum alloy materials with different impact times by laser shock peening are detected. Signal spectrum and phase velocity dispersion curves of SAWs are analyzed. Moreover, reasons for dispersion are discussed.展开更多
A novel dual-slab laser with an off-axis one-sided stable-unstable resonator which can compensate for thermal distortion to some extent by flipping the optical beam is described in this paper. The output power. effici...A novel dual-slab laser with an off-axis one-sided stable-unstable resonator which can compensate for thermal distortion to some extent by flipping the optical beam is described in this paper. The output power. efficiency, and near-field and far-field intensity distributions of the dual-slab laser have been studied. The results indicate that the novel dual-slab laser has better performance than the normal dual-slab laser with the same off-axis one-sided stable-unstable resonator.展开更多
文摘The thermal lens effect has emerged in recent years as a novel ,highly sensitive tool for the study of the very weak molecular absorption of light energy,This paper discusses the theory and technique of the thermal lens measurement.Some opplications of the thermal lens measurement are described.A mode-mismatched dual-beam thermal lens experimental arragement with a modulated probe beam ,designed by the authors.for trace analysis is presented,and its detection limit was found to be 4.1×10^-7 for Cu(Ⅱ) in ethanol and 80 mW excitation power.
文摘In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.
基金Ministry of Science and Technology of the People's Republic of China(MOST)(2016YFB1102402,2017YFB0405202)Key Laboratory of Opto-electronic Information Technology,Ministry of Education(Tianjin University),China(2019KFKT003)Shanghai Science and Technology Achievements Transformation and Industrialization project(18511109800).
文摘A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output power of 17.7 W is achieved by employing a 0.5 at.%doped sample,corresponding to an optical-to-optical efficiency of 46% with respect to the absorbed pump power.In addition,a numerical analysis and an experimental study of the temperature distribution,and thermal lens effect of the Nd:YVO4 thin disk,are presented considering the influence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor.The simulated results are in good agreement with the experimental results.
文摘Diode-laser pumped monolithic single-frequency non-planar ring laser has the advantages of compactness, reliability and high efficiency. But when the pump power is high enough, the thermal effect will be serious and the high-order transverse modes will appear. Therefore the single-mode output power is limited. In this paper, the mechanism of generating the high-order transverse modes in the monolithic unidirectional non-planar ring cavity is analyzed using ray tracing method. The calculated results are in agreement with the experiments.
基金supported by the National Natural Science Foundation of China under Grant No.60778006.
文摘Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves （SAWs） are dispersive when the near-surface properties of materials are changed. So the near-surface properties （such as the thickness of hardened layers, elastic properties, residual stresses, etc.） can be analyzed by the phase velocity dispersion. To study the propagation of SAWs in metal samples after peening, a more reasonable experimental method of broadband excitation and reception is introduced. The ultrasonic signals are excited by laser and received by polyvinylindene fluoride （PVDF） transducer. The SAW signals in aluminum alloy materials with different impact times by laser shock peening are detected. Signal spectrum and phase velocity dispersion curves of SAWs are analyzed. Moreover, reasons for dispersion are discussed.
文摘A novel dual-slab laser with an off-axis one-sided stable-unstable resonator which can compensate for thermal distortion to some extent by flipping the optical beam is described in this paper. The output power. efficiency, and near-field and far-field intensity distributions of the dual-slab laser have been studied. The results indicate that the novel dual-slab laser has better performance than the normal dual-slab laser with the same off-axis one-sided stable-unstable resonator.
