A low-numerical-aperture(NA)concept enables large-mode-area fiber with better single-mode operation ability,which is beneficial for transverse mode instability and nonlinear effects suppression.In this contribution,we...A low-numerical-aperture(NA)concept enables large-mode-area fiber with better single-mode operation ability,which is beneficial for transverse mode instability and nonlinear effects suppression.In this contribution,we reported a high-power fiber amplifier based on a piece of self-developed large-mode-area low-NA fiber with a core NA of 0.049 and a core/inner cladding diameter of 25/400μm.The influence of the pump wavelength and fiber length on the power scaling potential of the fiber amplifier is systematically investigated.As a result,an output of 4.80 kW and a beam quality factor of~1.33 were finally obtained,which is the highest output power ever reported in a fiber amplifier exploiting the low-NA fiber.The results reveal that low-NA fibers have superiority in power scaling and beam quality maintenance at high power levels.展开更多
A 2×3 kW-level bidirectional output fiber oscillator is realized by combining the specially designed spindle-shaped ytterbium-doped fiber,non-wavelength-stabilized 976-nm LDs,and grating bandwidth optimization to...A 2×3 kW-level bidirectional output fiber oscillator is realized by combining the specially designed spindle-shaped ytterbium-doped fiber,non-wavelength-stabilized 976-nm LDs,and grating bandwidth optimization to balance transverse mode instability and stimulated Raman scattering.The maximum output powers at both ends are 3265 and 2840 W,respectively,with a total efficiency of 73.2%.The M^(2) factors of the lasers at both ends are about 1.98 and 2.38,respectively.The beam profile at both ends shows that a bidirectional output annular beam fiber oscillator has been realized,which has great potential in practical applications.展开更多
A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid...A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid-state laser at 1 μm wavelength. Pulses as short as 182 ns were obtained from a ytterbium-doped（Yb:LGGG） bulk laser Q-switched by the MoS2 SAM, which we believe to be the shortest one ever achieved from the MoS2 SAs-based Q-switched bulk lasers. A maximum average output power of 0.6 W was obtained with a slope efficiency of 24%,corresponding to single pulse energy up to 1.8 μJ. In addition, the simultaneous dual-wavelength Q-switching at 1025.2 and 1028.1 nm has been successfully achieved. The results indicate the promising potential of few-layer MoS2 nanoplatelets as nonlinear optical switches for achieving efficient pulsed bulk lasers.展开更多
Power scaling based on traditional ytterbium-doped fibers(YDFs)is limited by optical nonlinear effects and transverse mode instability(TMI)in high-power fiber lasers.Here,we propose a novel long tapered fiber with a c...Power scaling based on traditional ytterbium-doped fibers(YDFs)is limited by optical nonlinear effects and transverse mode instability(TMI)in high-power fiber lasers.Here,we propose a novel long tapered fiber with a constant cladding and tapered core(CCTC)along its axis direction.The tapered-core region of the fiber is designed to enhance the stimulated Raman scattering(SRS)threshold and suppress higher-order mode resonance in the laser cavity.The CCTC YDF was fabricated successfully with a modified chemical vapor deposition(MCVD)method combined with solution doping technology,which has a cladding diameter of 400µm and a varying core with a diameter of~24μm at both ends and~31μm in the middle.To test the performance of the CCTC fiber during high-power operation,an all-fiber laser oscillator based on a CCTC YDF was investigated experimentally.As a result,a maximum output power of 3.42 kW was achieved with an optical-to-optical efficiency of 55.2%,although the TMI effect was observed at an output power of~3.12 kW.The measured beam quality(M^(2)factor)was~1.7,and no sign of the Raman component was observed in the spectrum.We believe that CCTC YDF has great potential to simultaneously mitigate the SRS and TMI effects,and further power scaling is promising by optimizing the structure of the YDF.展开更多
Stable picosecond dissipative soliton pulses were observed in an ytterbium-doped fber laser employing a high-quality mixture of BP/SnSe_(2)-PVA saturable absorber(SA).The modulation depth,saturation intensity,and non-...Stable picosecond dissipative soliton pulses were observed in an ytterbium-doped fber laser employing a high-quality mixture of BP/SnSe_(2)-PVA saturable absorber(SA).The modulation depth,saturation intensity,and non-saturable loss of the mixture of BP/SnSe_(2)-PVA SA were measured with values of 5.98%,18.37 MW/cm2,and 33%,respectively.Within the pump power range of 150–270 mW,stable dissipative soliton pulses were obtained with an output power of 1.68–4 mW.When the minimum pulse duration is 1.28 ps,a repetition rate of 0.903 MHz,center wavelength of 1064.38 nm and 3 dB bandwidth of 2 nm were obtained.The maximum pulse energy of 4.43 nJ and the signal-to-noise ratio up to 72 dB were achieved at pump power of 270 mW.The results suggest that the BP/SnSe_(2)-PVA mixture SA has outstanding nonlinear saturable absorption characteristics and broad ultrafast laser applications.展开更多
We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse ...We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse amplifier provides more than 10 mJ,approximately 1.2 ps pulses at 1030 nm to pump a three-stage optical parametric chirped pulse amplifier(OPCPA)based on bismuth borate crystals and to drive the supercontinuum seed in the YAG crystal.The energy of the amplified pulses in the wavelength range of 1.95–2.4μm reached 2.25 mJ with a pump-tosignal conversion efficiency of approximately 25%in the last OPCPA stage.These pulses were compressed to 38 fs in a pair of Suprasil 300 glass prisms.展开更多
A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation...A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μs.The highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 dB.The tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.展开更多
The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method tog...The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.展开更多
Physical, and spectral properties of a new com-mercial ytterbium doped phosphate laser glass with big size, NEW/Yb, was researched. Assessing from thermal mechani-cal property, nonlinear property, crystalline phase, m...Physical, and spectral properties of a new com-mercial ytterbium doped phosphate laser glass with big size, NEW/Yb, was researched. Assessing from thermal mechani-cal property, nonlinear property, crystalline phase, micro defects and spectroscopic properties of NEW/Yb and Kigre’s QX/Yb glasses, it is found that thermal-optical properties and glass internal quality of NEW/Yb glass are superior to QX/Yb glass. For NEW/Yb, the emission cross-section and fluorescent lifetime have a value of 0.53×10 pm2 and 2.2 ms, which are higher than those of QX/Yb.展开更多
Nd/Yb-co-doped YAG transparent ceramic nano-powder was prepared by a sol-gel combustion method.The structure,morphology and properties were characterized by thermogravimetric-differential thermal analysis,X-ray diffra...Nd/Yb-co-doped YAG transparent ceramic nano-powder was prepared by a sol-gel combustion method.The structure,morphology and properties were characterized by thermogravimetric-differential thermal analysis,X-ray diffraction,transmission electron microscopy,infrared spectroscopy,absorption analysis and fluorescence spectroscopy,respectively.The results show that the mass loss of the powder calcinated at 900 ℃ for 3 h is 49.56%.A well-crystallized Nd/Yb:YAG nano-powder with the superior sintering performance and high purity is obtained,and the morphology of the particles with the average diameter in the range of 60-100 runs appears regular.The nano-powder exhibits an intense absorption at 808 nm,corresponding to the 4I/9/2-4F7/2 transition of Nd^(^(3+) ions,which is suitable to absorb the wavelength of 808 nm from a laser diode source.The emission peak at 1046 nm of the Nd/Yb:YAG powder is more intense than that of Nd^(^(3+):YAG powder.It is indicated that the energy absorbed by Yb^(^(3+) ions from the laser diode source can be transmitted to Nd^(^(3+) ions based on the cross relaxation process of[(4F3/2)Nd,(2F7/2)Yb]-[(479/2)Nd,(2F5/2)Yb].展开更多
Recently, a number of studies have focused on micro-manufacturing processes, which find use in a variety of applications, including the production of microelectromechanical systems (MEMS). The process of ablation in m...Recently, a number of studies have focused on micro-manufacturing processes, which find use in a variety of applications, including the production of microelectromechanical systems (MEMS). The process of ablation in materials is mainly governed by the laser source and scanning speed. The rate of material ablation is influenced by chemical and physical properties. In this work, the energy from a CO<sub>2</sub> laser was used to ablate three different materials, namely, stainless steel 304L, a thin film of amorphous aluminum oxide (Al<sub>2</sub>O<sub>3</sub>), and pure silicon, due to their wide use in MEMS technology. The laser parameters used were an average power of 18 W and a spot size of 200 μm. The maximum depth during the photomechanical ablation process was 72 μm in the case of 304L steel and 77 μm in the case of the Al<sub>2</sub>O<sub>3</sub> thin film for a scan rate of 24 mm/min. However, at the same scan rate, silicon did not exhibit any penetration. As expected, while increasing scanning speed the ablation depth decreases due to reduced interaction time between laser and material. The theoretical ytterbium fiber laser shown in this study can thus be employed in the manufacturing of a wide variety of materials used in the production of MEMS as well as those used in clean energy technologies.展开更多
The superfluorescent Yb-doped fiber source operating near 980 nm is studied. The design requirement is theoretically discussed aiming to suppress the amplified spontaneous emission around 1030 nm in the 980-rim superf...The superfluorescent Yb-doped fiber source operating near 980 nm is studied. The design requirement is theoretically discussed aiming to suppress the amplified spontaneous emission around 1030 nm in the 980-rim superfluorescent fiber source. Based on the theoretical study, a multi-Watt, all-fiber, bi-directional, pumped, superfluorescent source operating near 980 nm is designed and experimentally demonstrated for the first time, to the best of our knowledge. The recorded 8.38-W combined output power is obtained with a 3-dB bandwidth about 3.5 nm. The power scaling of the 980-nm superlfuorescent fiber source is limited by the parasitic laser oscillation.展开更多
A large-mode-area（LMA） ytterbium-doped photonic crystal fiber（PCF） with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb3+/Al3+/F-/P5+ co-doped silica...A large-mode-area（LMA） ytterbium-doped photonic crystal fiber（PCF） with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb3+/Al3+/F-/P5+ co-doped silica glass containing 0.09 mol% Yb2O3 with an absorption coefficient at 976 nm up to 3.2 d B/m. The core glass with homogeneous distribution of Yb3+ ions and refractive index difference of 4 × 10-4 compared with pure silica was prepared by the sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 ps pulse duration and 48.7 MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W（266 k W peak power） quasi-single-mode laser output with M2 of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, stimulated Raman scattering, or thermal damage on the end facet of the fiber were observed.展开更多
We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temper...We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.展开更多
A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a cast...A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.展开更多
We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The osc...We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48nrn with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environ- ment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.展开更多
Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality...Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality are severe during the machining of SiCp/Al composites.Laser-induced oxidation is capable to improve the machinability of SiCp/Al composites.The material response of 55%(volume fraction)SiCp/Al composites induced by a nanosecond pulsed laser is studied.A metamorphic layer which is composed of an oxide layer and sub-layer is produced.The effects of reaction surrounding and laser average power on the microstructure and thickness of the oxide layer and sub-layer are investigated.Experimental results show that:A thicker oxide layer and a sub-layer are formed in an oxygen-rich atmosphere.The oxides are mainly composed of 2Al2O3·SiO2(mullite).A positive correlation between the laser average power and thicknesses of oxide layers and sub-layers is found.A loose oxide layer of 138μm and a sub-layer of 21μm are formed at the laser average power of 6 W,laser scanning pitch of 10μm,and laser scanning speed of 1 mm/s under an oxygen-rich atmosphere.The high efficient machining of Si Cp/Al composites can be realized by laser-induced oxidation.展开更多
基金supported by the National Key R&D Program of China(No.2022YFB3606000)State Key Laboratory of Pulsed Power Laser Technology(No.SKL2021ZR06)。
文摘A low-numerical-aperture(NA)concept enables large-mode-area fiber with better single-mode operation ability,which is beneficial for transverse mode instability and nonlinear effects suppression.In this contribution,we reported a high-power fiber amplifier based on a piece of self-developed large-mode-area low-NA fiber with a core NA of 0.049 and a core/inner cladding diameter of 25/400μm.The influence of the pump wavelength and fiber length on the power scaling potential of the fiber amplifier is systematically investigated.As a result,an output of 4.80 kW and a beam quality factor of~1.33 were finally obtained,which is the highest output power ever reported in a fiber amplifier exploiting the low-NA fiber.The results reveal that low-NA fibers have superiority in power scaling and beam quality maintenance at high power levels.
基金supported by the Funding for Distinguished Yong Scholars of Hunan Province(No.2023JJ10057)the Training Program for Excellent Young Innovations of Changsha(No.kq2305038)the Basic Scientific Research Program(No.JCKY2021525B015).
文摘A 2×3 kW-level bidirectional output fiber oscillator is realized by combining the specially designed spindle-shaped ytterbium-doped fiber,non-wavelength-stabilized 976-nm LDs,and grating bandwidth optimization to balance transverse mode instability and stimulated Raman scattering.The maximum output powers at both ends are 3265 and 2840 W,respectively,with a total efficiency of 73.2%.The M^(2) factors of the lasers at both ends are about 1.98 and 2.38,respectively.The beam profile at both ends shows that a bidirectional output annular beam fiber oscillator has been realized,which has great potential in practical applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51321091, 61275142, 61308042, and 91022003)China Postdoctoral Science Foundation (Grant Nos. 2013M531594, 2014T70633)
文摘A compact saturable absorber mirror（SAM） based on few-layer molybdenum disulfide（MoS2） nanoplatelets was fabricated and successfully used as an efficient saturable absorber（SA） for the passively Q-switched solid-state laser at 1 μm wavelength. Pulses as short as 182 ns were obtained from a ytterbium-doped（Yb:LGGG） bulk laser Q-switched by the MoS2 SAM, which we believe to be the shortest one ever achieved from the MoS2 SAs-based Q-switched bulk lasers. A maximum average output power of 0.6 W was obtained with a slope efficiency of 24%,corresponding to single pulse energy up to 1.8 μJ. In addition, the simultaneous dual-wavelength Q-switching at 1025.2 and 1028.1 nm has been successfully achieved. The results indicate the promising potential of few-layer MoS2 nanoplatelets as nonlinear optical switches for achieving efficient pulsed bulk lasers.
基金the National Natural Science Foundation of China(Nos.61735007 and 61705266).
文摘Power scaling based on traditional ytterbium-doped fibers(YDFs)is limited by optical nonlinear effects and transverse mode instability(TMI)in high-power fiber lasers.Here,we propose a novel long tapered fiber with a constant cladding and tapered core(CCTC)along its axis direction.The tapered-core region of the fiber is designed to enhance the stimulated Raman scattering(SRS)threshold and suppress higher-order mode resonance in the laser cavity.The CCTC YDF was fabricated successfully with a modified chemical vapor deposition(MCVD)method combined with solution doping technology,which has a cladding diameter of 400µm and a varying core with a diameter of~24μm at both ends and~31μm in the middle.To test the performance of the CCTC fiber during high-power operation,an all-fiber laser oscillator based on a CCTC YDF was investigated experimentally.As a result,a maximum output power of 3.42 kW was achieved with an optical-to-optical efficiency of 55.2%,although the TMI effect was observed at an output power of~3.12 kW.The measured beam quality(M^(2)factor)was~1.7,and no sign of the Raman component was observed in the spectrum.We believe that CCTC YDF has great potential to simultaneously mitigate the SRS and TMI effects,and further power scaling is promising by optimizing the structure of the YDF.
基金the National Natural Science Foundation of China(Grant No.62005094)the Natural Science Foundation of Shandong Province(No.ZR2021MF128)+2 种基金the Key Research Program of Shandong Province(No.2020JMRH0302)the Industrial Chain Program of Shandong Laser Equipment Innovation and Entrepreneurship Community(No.JGCYL2022-5)the Research Fund of University of Jinan(No.XKY1739).
文摘Stable picosecond dissipative soliton pulses were observed in an ytterbium-doped fber laser employing a high-quality mixture of BP/SnSe_(2)-PVA saturable absorber(SA).The modulation depth,saturation intensity,and non-saturable loss of the mixture of BP/SnSe_(2)-PVA SA were measured with values of 5.98%,18.37 MW/cm2,and 33%,respectively.Within the pump power range of 150–270 mW,stable dissipative soliton pulses were obtained with an output power of 1.68–4 mW.When the minimum pulse duration is 1.28 ps,a repetition rate of 0.903 MHz,center wavelength of 1064.38 nm and 3 dB bandwidth of 2 nm were obtained.The maximum pulse energy of 4.43 nJ and the signal-to-noise ratio up to 72 dB were achieved at pump power of 270 mW.The results suggest that the BP/SnSe_(2)-PVA mixture SA has outstanding nonlinear saturable absorption characteristics and broad ultrafast laser applications.
基金This research was sponsored by the Research Council of Lithuania under contract S-MIP-21-30.Two of the authors are grateful for NATO SPS G5734 fellowships.
文摘We present a compact and cost-effective mJ-level femtosecond laser system operating at a center wavelength of approximately 2.15μm.An affordable two-stage ytterbium-doped yttrium aluminum garnet(Yb:YAG)chirped pulse amplifier provides more than 10 mJ,approximately 1.2 ps pulses at 1030 nm to pump a three-stage optical parametric chirped pulse amplifier(OPCPA)based on bismuth borate crystals and to drive the supercontinuum seed in the YAG crystal.The energy of the amplified pulses in the wavelength range of 1.95–2.4μm reached 2.25 mJ with a pump-tosignal conversion efficiency of approximately 25%in the last OPCPA stage.These pulses were compressed to 38 fs in a pair of Suprasil 300 glass prisms.
基金the Ministry of Higher Education,MOHE,for funding this work under Grant LRGS(2015) NGOD/UM/KPTthe University of Malaya,UM,for funding this work under Grant RU 001–2017
文摘A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μs.The highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 dB.The tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.
基金supported by the National Research Foundation of Korea funded by the Korean Government(MSIT),South Korea(Grant Nos.NRF-2015R1A2A2A11000907 and NRF-2015R1A2A2A04006979)Ministry of Science and ICT(MSIT),Korea,under the Information Technology Research Center(ITRC)support program(IITP-2017-2015-0-00385),supervised by the Institute for Information and Communications Technology Promotion(IITP)
文摘The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 69988006) the National Program of "863" High-Tech Plan.
文摘Physical, and spectral properties of a new com-mercial ytterbium doped phosphate laser glass with big size, NEW/Yb, was researched. Assessing from thermal mechani-cal property, nonlinear property, crystalline phase, micro defects and spectroscopic properties of NEW/Yb and Kigre’s QX/Yb glasses, it is found that thermal-optical properties and glass internal quality of NEW/Yb glass are superior to QX/Yb glass. For NEW/Yb, the emission cross-section and fluorescent lifetime have a value of 0.53×10 pm2 and 2.2 ms, which are higher than those of QX/Yb.
基金supported by special project of Changchun Science & Technology Office(2014228)the Development and Reform Commission of Jilin Province(2015Y69)
文摘Nd/Yb-co-doped YAG transparent ceramic nano-powder was prepared by a sol-gel combustion method.The structure,morphology and properties were characterized by thermogravimetric-differential thermal analysis,X-ray diffraction,transmission electron microscopy,infrared spectroscopy,absorption analysis and fluorescence spectroscopy,respectively.The results show that the mass loss of the powder calcinated at 900 ℃ for 3 h is 49.56%.A well-crystallized Nd/Yb:YAG nano-powder with the superior sintering performance and high purity is obtained,and the morphology of the particles with the average diameter in the range of 60-100 runs appears regular.The nano-powder exhibits an intense absorption at 808 nm,corresponding to the 4I/9/2-4F7/2 transition of Nd^(^(3+) ions,which is suitable to absorb the wavelength of 808 nm from a laser diode source.The emission peak at 1046 nm of the Nd/Yb:YAG powder is more intense than that of Nd^(^(3+):YAG powder.It is indicated that the energy absorbed by Yb^(^(3+) ions from the laser diode source can be transmitted to Nd^(^(3+) ions based on the cross relaxation process of[(4F3/2)Nd,(2F7/2)Yb]-[(479/2)Nd,(2F5/2)Yb].
文摘Recently, a number of studies have focused on micro-manufacturing processes, which find use in a variety of applications, including the production of microelectromechanical systems (MEMS). The process of ablation in materials is mainly governed by the laser source and scanning speed. The rate of material ablation is influenced by chemical and physical properties. In this work, the energy from a CO<sub>2</sub> laser was used to ablate three different materials, namely, stainless steel 304L, a thin film of amorphous aluminum oxide (Al<sub>2</sub>O<sub>3</sub>), and pure silicon, due to their wide use in MEMS technology. The laser parameters used were an average power of 18 W and a spot size of 200 μm. The maximum depth during the photomechanical ablation process was 72 μm in the case of 304L steel and 77 μm in the case of the Al<sub>2</sub>O<sub>3</sub> thin film for a scan rate of 24 mm/min. However, at the same scan rate, silicon did not exhibit any penetration. As expected, while increasing scanning speed the ablation depth decreases due to reduced interaction time between laser and material. The theoretical ytterbium fiber laser shown in this study can thus be employed in the manufacturing of a wide variety of materials used in the production of MEMS as well as those used in clean energy technologies.
基金Project supported by the National Natural Science Foundation of China(Grant No.61405249)
文摘The superfluorescent Yb-doped fiber source operating near 980 nm is studied. The design requirement is theoretically discussed aiming to suppress the amplified spontaneous emission around 1030 nm in the 980-rim superfluorescent fiber source. Based on the theoretical study, a multi-Watt, all-fiber, bi-directional, pumped, superfluorescent source operating near 980 nm is designed and experimentally demonstrated for the first time, to the best of our knowledge. The recorded 8.38-W combined output power is obtained with a 3-dB bandwidth about 3.5 nm. The power scaling of the 980-nm superlfuorescent fiber source is limited by the parasitic laser oscillation.
基金financially supported by the National High Technology Research and Development Program of China(No.2016YFB0402201)
文摘A large-mode-area（LMA） ytterbium-doped photonic crystal fiber（PCF） with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb3+/Al3+/F-/P5+ co-doped silica glass containing 0.09 mol% Yb2O3 with an absorption coefficient at 976 nm up to 3.2 d B/m. The core glass with homogeneous distribution of Yb3+ ions and refractive index difference of 4 × 10-4 compared with pure silica was prepared by the sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 ps pulse duration and 48.7 MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W（266 k W peak power） quasi-single-mode laser output with M2 of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, stimulated Raman scattering, or thermal damage on the end facet of the fiber were observed.
基金This work is partially supported by the Fundacao para a Ciencia e a Tecnologia(grant agreement No.PD/BD/135222/2017)has been carried out within the framework of Laserlab-Portugal(National Roadmap of Research Infrastructures,22124)the European Union Horizon 2020 research and innovation program under grant agreement No.654148 Laserlab-Europe.
文摘We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.
基金This work was supported in part by the Airlangga University(Grant No.804/UN3.15/PT/2021)the University of Malaya(Grant No.ML001-2017).
文摘A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2013AA031501the Fundamental Research Funds for the Central Universities under Grant No 2014TS017
文摘We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48nrn with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environ- ment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.
基金supported by the National Natural Science Foundation of China(Nos.51705249, 52075255)the China Postdoctoral Science Foundation (No.2019M661823)
文摘Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al composites)are widely used in aviation,aerospace and electronic package.However,low machining efficiency,severe tool wear and poor surface quality are severe during the machining of SiCp/Al composites.Laser-induced oxidation is capable to improve the machinability of SiCp/Al composites.The material response of 55%(volume fraction)SiCp/Al composites induced by a nanosecond pulsed laser is studied.A metamorphic layer which is composed of an oxide layer and sub-layer is produced.The effects of reaction surrounding and laser average power on the microstructure and thickness of the oxide layer and sub-layer are investigated.Experimental results show that:A thicker oxide layer and a sub-layer are formed in an oxygen-rich atmosphere.The oxides are mainly composed of 2Al2O3·SiO2(mullite).A positive correlation between the laser average power and thicknesses of oxide layers and sub-layers is found.A loose oxide layer of 138μm and a sub-layer of 21μm are formed at the laser average power of 6 W,laser scanning pitch of 10μm,and laser scanning speed of 1 mm/s under an oxygen-rich atmosphere.The high efficient machining of Si Cp/Al composites can be realized by laser-induced oxidation.
