| Dual-wavelength lasers play an important role in areas of precision measurement,differential spectroscopy,biomedical Science,frequency conversion,and so on.In addition to combining two independent lasers,the main methods to generate dual-wavelength lasers are using different spectrum lines of the laser gain medium or optical parametric oscillators.However,there are generally disadvantages such as complex structure,unstable power,non-adjustable power ratio and pulse interval between two wavelengths.In order to solve the above problems,this dissertation proposes a novel dual-wavelength solid-state laser based on the coaxial diode-end-pumped dual-crystals configuaration,and carries out related theoretical and experimental research.Based on the dual-wavelength fundamental lasers near 1.06-?m,the stable output of dual-wavelength lasers with adjustable power ratio and pulse interval in different bands and terahertz wave are achieved through nonlinear optical frequency conversion technologies such as frequency doubling,sum frequency,optical parametric oscillation(OPO),stimulated Raman scattering and difference frequency generation(DFG).The main work and innovations are summarized as follows:1.The heat conduction equation and thermal lens formula in the coaxial diode-end-pumped configuaration were established.The effects of the pump beam radius and pump beam waist position on the temperature distribution of the crystal and thermal focal length were theoretically analyzed.The rate equations of the dual-wavelength laser based on the coaxial diode-end-pumped configuaration and its intrcavity frequency doubling,optical parametric oscillation and Raman laser were established.The influences of the pump beam waist position on the output power ratio and pulse interval between two wavelengths were analyzed.2.Based on the coaxial diode-end-pumped configuaration,using the combination of Nd:YAG/Nd:YLF,different dual-wavelength lasers in the 1?m band were obtained.By optimizing the resonant cavity and using the combination of Nd:YAG/Nd:YAP,the total output power of 1064 nm and 1079 nm dual-wavelength lasers with approximately equal power was 15.5 W,corresponding to the optical-optical conversion efficiency of 38.8%.Using the combination of Nd:YVO4/Nd:Gd VO4,the KTP and LBO were worked as nonlinear crystals for intrcavity frequency doubling.The maximum continuous-wave output power and pulsed output power of532.2nm/531.9nm/531.6nm multi-wavelength green lasers were 4.5 W and 3.77 W,and the optical-optical conversion efficiency were 21.8%and 22.4%,respectively.3.Based on coaxial diode-end-pumped configuaration,the active Q-switched Nd:YAG/Nd:YLF/KTA intrcavity optical parametric oscillator and Raman laser were demonstrated,respectively.The output powers of dual-wavelength signal waves with1.5-1.55?m band and dual-wavelength Stokes with 1.17-1.2?m band were 724 m W and 1.79 W,corresponding to optical-optical conversion efficiency of 7.24%and11.3%,respectively.Synchronized pulse widths of dual-wavelength signal waves and dual-wavelength Stokes were 6 ns and 4 ns.By moving the beam waist position of the pump light,the dual-wavelength power adjustment ratio of 50%to 200%and the pulse interval adjustment range of±60ns can be effectively achieved.4.The terahertz source using difference frequency generation(DFG)based on the actively Q-switch a-cut Nd:YLF/c-cut Nd:YLF laser was demonstrated.Using the coaxial diode-end-pumped laser,the total output powers of 2.92 W of1047nm/1053nm lasers with orthogonal polarization was obtained.Where the GaSe worked as nonlinear crystal,the maximum average output power of 1.64 THz was0.93?W with the energy conversion efficiency of 3.3×10-7,corresponding photon conversion efficiency was 1.15×10-4. |
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