Investigation On All-solid-state Orthogonally Polarized Dual-wavelength Nd:YLF Lasers

All solid-state lasers are widely used in many fields such as national defense,material processing,medicine,communication due to their high reliability,stability,high efficiency and easy operation.With the expansion of applications,lasers with a single wavelength have not been able to meet the needs in some fields.Nowadays,simultaneous dual-wavelength emission has applications in various fields,such as holography,laser spectroscopy,medical,differential lidar,and the generation of terahertz(THz)radiations.Especially,the dual-wavelength lasers with orthogonal polarizations have shown great potential for laser interferometry and precision metrology due to their unique intrinsic properties.In this dissertation,detailed researches on the Q-switched orthogonally polarized dual-wavelength fundamental laser and Raman laser are presented in experiments.The main achievements are described as follows:1.A high average power diode end-pumped orthogonally polarized dual-wavelength Nd:YLF laser at 1047 and 1053 nm had been demonstrated for both continuous wave(CW)and pulsed operations.Several strategies had been employed to effectively reduce the maximum tensile stress and the energy-transfer upconversion(ETU)effect in the Nd:YLF crystal.The Nd:YLF laser delivered a maximum CW output power of 14.2 W under the incident power of 41.2 W with an optical-to-optical conversion efficiency of 34.1%and a slope efficiency of 38.3%.Active Q-switching(AQS)was accomplished by inserting an acousto-optic modulator in the cavity.Under the incident pump power of 40 W,the setup delivered a maximum average output power of 10 W at the pulse repetition frequency(PRF)of 30 kHz and a largest pulse energy of 3.4 mJ at the PRF of 1 kHz,respectively.To the best of our knowledge,these are the highest average output powers for both CW and AQS orthogonally polarized dual-wavelength lasers based on laser crystals.2.A simultaneous orthogonally-polarized dual-wavelength passively Q-switched Nd:YLF/Cr⁴⁺:YAG laser have been demonstrated by combining two laser crystals in a double-resonator configuration.Under the total incident pump power of 46.1 W,the maximum average output powers at 1047 and 1053 nm were up to 4.5 and 4.2 W with the pulse repetition frequency(PRF)of 6 kHz,respectively,corresponding to a total optical-to-optical conversion efficiency of18.7%.3.We present the first demonstration of an actively Q-switched orthogonally polarized dual-wavelength Nd:YLF/YVO₄ Raman laser to our knowledge.A maximum dual wavelength Raman output power of 4.5 W was obtained,which contained a 2.5 W Raman component at 1155 nm and a 2.0 W Raman component at 1162 nm,under the incident pump power of 46.1 W and pulse repetition frequency of 5 kHz.The corresponding peak powers were as high as 178.6 and 142.9kW,respectively.As far as we know,we have increased the orthogonally polarized dual-wavelength Raman average output power by six times.