high-power, high-energy Ho：YAG oscillator resonantly pumped by a Tm-doped fiber laser is presented. A maximum continuous output power of 38 W with a slope efficiency of 51.9% is achieved at the wavelength of 2.09 μm...high-power, high-energy Ho：YAG oscillator resonantly pumped by a Tm-doped fiber laser is presented. A maximum continuous output power of 38 W with a slope efficiency of 51.9% is achieved at the wavelength of 2.09 μm, and M2≈1.48. In the Q-switching regime, the maximum pulse energy of 12.8 mJ, corresponding to a 514.5 kW peak power, is obtained at the pulse repetition frequency of 1 kHz. Furthermore, the thermal lens effect of the system is studied theoretically, and the radius of the transverse electromagnetic（TEM_（00）） mode of the laser crystal under different pump powers is given.展开更多
A high pulse repetition frequency（PRF）, high energy Ho：YAG laser directly pumped by a Tm-doped fiber laser and its application to a mid-infrared ZnGeP_2（ZGP） optical parametric oscillator（OPO） is demonstrated.T...A high pulse repetition frequency（PRF）, high energy Ho：YAG laser directly pumped by a Tm-doped fiber laser and its application to a mid-infrared ZnGeP_2（ZGP） optical parametric oscillator（OPO） is demonstrated.The maximum polarized 2.09 μm laser pulse energy is 13.46 mJ at a PRF of 1 k Hz. The corresponding peak power reaches 504 kW. In a double-resonant ZGP-OPO, a maximum mid-infrared laser pulse energy of 1.25 m J,corresponding to a peak power of 79 kW, is accomplished at a PRF of 3 kHz. The nonlinear conversion efficiency reaches 41.7%. The nonlinear slope efficiency reaches 53.3%.展开更多
The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated ...The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated to be Ω2 =6.74 × 10^-20cm^2,Ω4 = 1.20 × 10^-20cm^2, and Ω6= 0.66 × 10^-20cm^2, and the fluorescence branching ratios and radiative lifetimes for a series of excited state manifolds are also determined. The emission cross sections with our measured infrared luminescence spectra, especially important for 4.1 μm, are calculated to be about 4.37 × 10^-21cm^2. The crystal quality is preliminarily tested through a mid-infrared laser emission experiment.展开更多
The generation of mid-infrared pulsed lasers was achieved in a Ho3+:YAG laser pumped gain-switched Cr^2+:Cd Se laser system with the shortest pulse duration of 4.15 ns.With a pump pulse duration of 50 ns and pump powe...The generation of mid-infrared pulsed lasers was achieved in a Ho3+:YAG laser pumped gain-switched Cr^2+:Cd Se laser system with the shortest pulse duration of 4.15 ns.With a pump pulse duration of 50 ns and pump power of 2.7 W,the gain-switched Cr^2+:Cd Se laser achieved over 10 times pulse narrowing,obtaining the maximum peak power of 5.7 k W.The optical-to-optical conversion efficiency was 3.7%,which could be further improved with better crystal surface polishing quality.The laser central wavelength was measured to be 2.65μm with a bandwidth(FWHM)of 50 nm.In addition,the parameter optimization for suppressing the pulse tail was discussed,while the long cavity and high output transmissivity contributed to obtaining the single-peak pulses.展开更多
The ultimate capacity of a cladding-pumped 10/130 Tm:fiber is experimentally investigated with a 793 nm laser diode bidirectionally pumped amplifier. The laser system works stably at the output powers of 52 W,65 W, an...The ultimate capacity of a cladding-pumped 10/130 Tm:fiber is experimentally investigated with a 793 nm laser diode bidirectionally pumped amplifier. The laser system works stably at the output powers of 52 W,65 W, and 87 W. Eventually, the damage of the amplifier occurs when the output power reaches about 103.5 W with a total incident pump power of 176.8 W. Considering the incident seed power of 12.3 W,the amplifier conversion efficiency is estimated to be about 51.6% before it is damaged. With valuable exploration, we achieve the first air-cooling 60 W Tm:fiber laser at 1945.845 nm with a spectral linewidth of 0.4 nm.The laser power stability reaches 1.24% during a continuous test time of >65 h. The beam quality is measured as M_x^2=1.16 and M_y^2=1.14.展开更多
The steady-state gain distribution in cladding pumped thulium-doped fiber laser（TDFL） is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With ...The steady-state gain distribution in cladding pumped thulium-doped fiber laser（TDFL） is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition（OFI） and always occurs in tandem TDFL-Ho：YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho：YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.展开更多
基金supported by the National Natural Science Foundation of China(No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(No.20120002110066)the Special Program of Co-Construction with the Beijing Municipal Government of China(No.20121000302)
文摘high-power, high-energy Ho：YAG oscillator resonantly pumped by a Tm-doped fiber laser is presented. A maximum continuous output power of 38 W with a slope efficiency of 51.9% is achieved at the wavelength of 2.09 μm, and M2≈1.48. In the Q-switching regime, the maximum pulse energy of 12.8 mJ, corresponding to a 514.5 kW peak power, is obtained at the pulse repetition frequency of 1 kHz. Furthermore, the thermal lens effect of the system is studied theoretically, and the radius of the transverse electromagnetic（TEM_（00）） mode of the laser crystal under different pump powers is given.
基金supported by the National Natural Science Foundation of China(No.61275146)the National Key Research and Development Program of China(No.2016YFB0402104)
文摘A high pulse repetition frequency（PRF）, high energy Ho：YAG laser directly pumped by a Tm-doped fiber laser and its application to a mid-infrared ZnGeP_2（ZGP） optical parametric oscillator（OPO） is demonstrated.The maximum polarized 2.09 μm laser pulse energy is 13.46 mJ at a PRF of 1 k Hz. The corresponding peak power reaches 504 kW. In a double-resonant ZGP-OPO, a maximum mid-infrared laser pulse energy of 1.25 m J,corresponding to a peak power of 79 kW, is accomplished at a PRF of 3 kHz. The nonlinear conversion efficiency reaches 41.7%. The nonlinear slope efficiency reaches 53.3%.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110066)the Special Program of the Co-construction with Beijing Municipal Government of China(Grant No.20121000302)
文摘The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated to be Ω2 =6.74 × 10^-20cm^2,Ω4 = 1.20 × 10^-20cm^2, and Ω6= 0.66 × 10^-20cm^2, and the fluorescence branching ratios and radiative lifetimes for a series of excited state manifolds are also determined. The emission cross sections with our measured infrared luminescence spectra, especially important for 4.1 μm, are calculated to be about 4.37 × 10^-21cm^2. The crystal quality is preliminarily tested through a mid-infrared laser emission experiment.
基金supported by the National Key Research and Development Program of China(No.2017YFB1104500)the China Postdoctoral Science Foundation(No.2018M630355)the National Natural Science Foundation of China(Nos.61905128 and61905150)。
文摘The generation of mid-infrared pulsed lasers was achieved in a Ho3+:YAG laser pumped gain-switched Cr^2+:Cd Se laser system with the shortest pulse duration of 4.15 ns.With a pump pulse duration of 50 ns and pump power of 2.7 W,the gain-switched Cr^2+:Cd Se laser achieved over 10 times pulse narrowing,obtaining the maximum peak power of 5.7 k W.The optical-to-optical conversion efficiency was 3.7%,which could be further improved with better crystal surface polishing quality.The laser central wavelength was measured to be 2.65μm with a bandwidth(FWHM)of 50 nm.In addition,the parameter optimization for suppressing the pulse tail was discussed,while the long cavity and high output transmissivity contributed to obtaining the single-peak pulses.
基金the China Postdoctoral Science Foundation(No.2018M630355)the National Natural Science Foundation of China(No.61905150)the Characteristic Innovation Projects of Scientific Research in Universities of Guangdong Province(Natural Science)(No.2018KTSCX348).
文摘The ultimate capacity of a cladding-pumped 10/130 Tm:fiber is experimentally investigated with a 793 nm laser diode bidirectionally pumped amplifier. The laser system works stably at the output powers of 52 W,65 W, and 87 W. Eventually, the damage of the amplifier occurs when the output power reaches about 103.5 W with a total incident pump power of 176.8 W. Considering the incident seed power of 12.3 W,the amplifier conversion efficiency is estimated to be about 51.6% before it is damaged. With valuable exploration, we achieve the first air-cooling 60 W Tm:fiber laser at 1945.845 nm with a spectral linewidth of 0.4 nm.The laser power stability reaches 1.24% during a continuous test time of >65 h. The beam quality is measured as M_x^2=1.16 and M_y^2=1.14.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110066)the Special Program of the Co-construction with Beijing Municipal Government of China(Grant No.20121000302)
文摘The steady-state gain distribution in cladding pumped thulium-doped fiber laser（TDFL） is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition（OFI） and always occurs in tandem TDFL-Ho：YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho：YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.
