The coupling efficiency of the beam combination and the fiber-coupled module is limited due to the large vertical divergent angle of conventional semiconductor laser diodes. We present a high coupling efficiency modul...The coupling efficiency of the beam combination and the fiber-coupled module is limited due to the large vertical divergent angle of conventional semiconductor laser diodes. We present a high coupling efficiency module using photonic-band-crystal （PBC） laser diodes with narrow vertical divergent angles. Three PBC single-emitter laser diodes are combined into a fiber with core diameter of 105μm and numerical aperture of 0.22. A high coupling efficiency of 94.4% is achieved and the brightness is calculated to be 1.T MW/（cm2.sr） with the injection current of 8A.展开更多
Performances of blue and green laser diodes（LDs） with different u-InGaN upper waveguides（UWGs） are investigated theoretically by using LASTIP. It is found that the slope efficiency（SE） of blue LD decreases due t...Performances of blue and green laser diodes（LDs） with different u-InGaN upper waveguides（UWGs） are investigated theoretically by using LASTIP. It is found that the slope efficiency（SE） of blue LD decreases due to great optical loss when the indium content of u-InGaN UWG is more than 0.02, although its leakage current decreases obviously. Meanwhile the SE of the green LD increases when the indium content of u-InGaN UWG is varied from 0 to 0.05, which is attributed to the reduction of leakage current and the small increase of optical loss. Therefore, a new blue LD structure with In（0.05） Ga（0.95）N lower waveguide（LWG） is designed to reduce the optical loss, and its slope efficiency is improved significantly.展开更多
An efficient narrow=linewidth single-frequency （SF） Yb-doped all-fiber master oscillator power amplifier （MOPA） laser operating at 1064.3 nm is demonstrated experimentally. A ring cavity SF fiber laser is used as ...An efficient narrow=linewidth single-frequency （SF） Yb-doped all-fiber master oscillator power amplifier （MOPA） laser operating at 1064.3 nm is demonstrated experimentally. A ring cavity SF fiber laser is used as the seed source for the MOPA system and the Yb-doped fibers are employed as the gain medium or the saturable absorber. The SF operation is observed to be stable without mode hopping. The highest output power of 266 mW is obtained under the 400row pump power with the corresponding slope efficiency of 66.2-. The Hnewidth of the amplified output laser is approximately I kHz and its optical signal-to-noise ratio is over 45 dB.展开更多
Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was...Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was used to study the dynamics of nonequilibrium charge carriers in both textured and non-textured GaAs substrates.Our findings show that the textured surface acts as an antireflective layer, greatly boosting the infrared pump laser's coupling efficiency into the semi-insulating GaAs substrate. Additionally, texturing introduces a trapassisted recombination pathway, speeding up carrier relaxation and thus reducing Joule heating. Under the same pumping and bias field conditions, the coarse-textured GaAs photoconductive antenna shows nearly 7.85 times stronger THz emission amplitude than the non-textured device, along with improvement in signal-to-noise ratio.At a fixed bias field, higher pump power increases photogenerated carrier density, causing bias field screening and subsequent saturation of THz emission. At fixed pump power, when the bias field reaches ~2.5 kV/cm, both THz emission and photocurrent spectra show a clear kink, signaling intervalley scattering from the Γ valley to the L(X) valleys under high electric fields.展开更多
We demonstrate a high-efficiency and high-power quasi-three-level laser based on a trapezoidal composite slab architecture with a 270μm-thick Yb-doping surface.The design of a surface-doped slab architecture,temperat...We demonstrate a high-efficiency and high-power quasi-three-level laser based on a trapezoidal composite slab architecture with a 270μm-thick Yb-doping surface.The design of a surface-doped slab architecture,temperature effects,laser oscillator model,and laser oscillator experiments with a surface-doped slab as a laser host medium have been presented.By theoretical calculation,the temperature rise in the surface-doped slab is only one seventh of that in the bulk-doped slab at the same maximum pump power of 30 kW.Finally,in the laser oscillator experiments,an output energy of 21.6 J is obtained when the pump energy is 48 J with a repetition rate of 5 Hz and a pulse width of 1 ms.The optical-optical efficiency is 45%.展开更多
Laser power transmission(LPT)technology has gained significant attention in recent years due to its potential to revolutionize energy transfer in a more efficient,safe,and eco-friendly manner.Compared to traditional w...Laser power transmission(LPT)technology has gained significant attention in recent years due to its potential to revolutionize energy transfer in a more efficient,safe,and eco-friendly manner.Compared to traditional wired power transmission,LPT offers contactless transmission,high efficiency,and enhanced safety.This technology has the potential to significantly improve energy transmission efficiency,reduce energy loss,and minimize environmental pollution.Additionally,LPT can provide wireless power supply to mobile devices,robots,and aerospace vehicles,which can enhance device reliability and lifespan.Herein,this emerging technology could revolutionize how power is transmitted and utilized,ushering in major progress for the energy sector going forward.In this review,we provide a brief introduction to the LPT system.Then we present the development history and current status of each module separately.Following that,we introduce the expansion of the LPT system in space and underwater applications.Finally,we discuss the challenge of realizing a highly efficient LPT system and offer our perspectives on future opportunities and study directions.展开更多
Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstr...Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstrated that codoping with Y3＋ ions could efficiently improve the spectroscopic properties. Tm;Y：CaF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections, and much longer fluorescence lifetimes of the upper laser level（Tm3＋：3H4 level） than Tm：CaF2 crystals. Continuous-wave（CW） lasers around 1.97 μm were demonstrated in 4.0 at. % Tm,4.0 at. % Y：CaF2 single crystals under 792 nm laser diode（LD） pumping. The best laser performance has been demonstrated with a low threshold of 0.368 W, a high slope efficiency of 54.8%, and a maximum output power of 1.013 W.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61535013,61321063 and 61404133the National Key Research and Development Program of China under Grant Nos 2016YFB0402203,2016YFB0401804 and2016YFA0301102the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2014096
文摘The coupling efficiency of the beam combination and the fiber-coupled module is limited due to the large vertical divergent angle of conventional semiconductor laser diodes. We present a high coupling efficiency module using photonic-band-crystal （PBC） laser diodes with narrow vertical divergent angles. Three PBC single-emitter laser diodes are combined into a fiber with core diameter of 105μm and numerical aperture of 0.22. A high coupling efficiency of 94.4% is achieved and the brightness is calculated to be 1.T MW/（cm2.sr） with the injection current of 8A.
基金Project supported by the National Key R&D Program of China(Grant Nos.2016YFB0400803 and 2016YFB0401801)the National Natural Science Foundation of China(Grant Nos.61674138,61674139,61604145,61574135,61574134,61474142,61474110,61377020,and 61376089)+1 种基金the Science Challenge Project,China(Grant No.TZ2016003)the Beijing Municipal Science and Technology Project,China(Grant No.Z161100002116037)
文摘Performances of blue and green laser diodes（LDs） with different u-InGaN upper waveguides（UWGs） are investigated theoretically by using LASTIP. It is found that the slope efficiency（SE） of blue LD decreases due to great optical loss when the indium content of u-InGaN UWG is more than 0.02, although its leakage current decreases obviously. Meanwhile the SE of the green LD increases when the indium content of u-InGaN UWG is varied from 0 to 0.05, which is attributed to the reduction of leakage current and the small increase of optical loss. Therefore, a new blue LD structure with In（0.05） Ga（0.95）N lower waveguide（LWG） is designed to reduce the optical loss, and its slope efficiency is improved significantly.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61475125 and 61505162the Foundation of the Education Committee of Shaanxi Province under Grant Nos 16JK1769 and l4JK1756the Science Foundation of Northwest University under Grant Nos 15NW07 and 13NW14
文摘An efficient narrow=linewidth single-frequency （SF） Yb-doped all-fiber master oscillator power amplifier （MOPA） laser operating at 1064.3 nm is demonstrated experimentally. A ring cavity SF fiber laser is used as the seed source for the MOPA system and the Yb-doped fibers are employed as the gain medium or the saturable absorber. The SF operation is observed to be stable without mode hopping. The highest output power of 266 mW is obtained under the 400row pump power with the corresponding slope efficiency of 66.2-. The Hnewidth of the amplified output laser is approximately I kHz and its optical signal-to-noise ratio is over 45 dB.
基金supported by the National Key Research and Development Program of China (Grant No.2023YFF0719200)the National Natural Science Foundation of China (Grant Nos.62322115,U24A20226,62588201,62435010,and 62335012)+2 种基金the 111 Project (Grant No.D18014)the Key project supported by Science and Technology Commission Shanghai Municipality (Grant No.YDZX20193100004960)Science and Technology Commission of Shanghai Municipality (Grant Nos.22JC1400200 and 21S31907400)。
文摘Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was used to study the dynamics of nonequilibrium charge carriers in both textured and non-textured GaAs substrates.Our findings show that the textured surface acts as an antireflective layer, greatly boosting the infrared pump laser's coupling efficiency into the semi-insulating GaAs substrate. Additionally, texturing introduces a trapassisted recombination pathway, speeding up carrier relaxation and thus reducing Joule heating. Under the same pumping and bias field conditions, the coarse-textured GaAs photoconductive antenna shows nearly 7.85 times stronger THz emission amplitude than the non-textured device, along with improvement in signal-to-noise ratio.At a fixed bias field, higher pump power increases photogenerated carrier density, causing bias field screening and subsequent saturation of THz emission. At fixed pump power, when the bias field reaches ~2.5 kV/cm, both THz emission and photocurrent spectra show a clear kink, signaling intervalley scattering from the Γ valley to the L(X) valleys under high electric fields.
基金funded by the Science and Technology on Solid-State Laser Laboratory
文摘We demonstrate a high-efficiency and high-power quasi-three-level laser based on a trapezoidal composite slab architecture with a 270μm-thick Yb-doping surface.The design of a surface-doped slab architecture,temperature effects,laser oscillator model,and laser oscillator experiments with a surface-doped slab as a laser host medium have been presented.By theoretical calculation,the temperature rise in the surface-doped slab is only one seventh of that in the bulk-doped slab at the same maximum pump power of 30 kW.Finally,in the laser oscillator experiments,an output energy of 21.6 J is obtained when the pump energy is 48 J with a repetition rate of 5 Hz and a pulse width of 1 ms.The optical-optical efficiency is 45%.
基金supported by the National Natural Science Foundation of China(62104234 and 52103279)the Shanghai Sailing Program,China(21YF1454000)the National Key R&D Program of China(2018YFE0118000).
文摘Laser power transmission(LPT)technology has gained significant attention in recent years due to its potential to revolutionize energy transfer in a more efficient,safe,and eco-friendly manner.Compared to traditional wired power transmission,LPT offers contactless transmission,high efficiency,and enhanced safety.This technology has the potential to significantly improve energy transmission efficiency,reduce energy loss,and minimize environmental pollution.Additionally,LPT can provide wireless power supply to mobile devices,robots,and aerospace vehicles,which can enhance device reliability and lifespan.Herein,this emerging technology could revolutionize how power is transmitted and utilized,ushering in major progress for the energy sector going forward.In this review,we provide a brief introduction to the LPT system.Then we present the development history and current status of each module separately.Following that,we introduce the expansion of the LPT system in space and underwater applications.Finally,we discuss the challenge of realizing a highly efficient LPT system and offer our perspectives on future opportunities and study directions.
基金financially supported by the National Natural Science Foundation of China(Nos.61422511,61635012,and 51432007)the Strategic Priority Program of the Chinese Academy of Sciences(No.XDB16030000)
文摘Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstrated that codoping with Y3＋ ions could efficiently improve the spectroscopic properties. Tm;Y：CaF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections, and much longer fluorescence lifetimes of the upper laser level（Tm3＋：3H4 level） than Tm：CaF2 crystals. Continuous-wave（CW） lasers around 1.97 μm were demonstrated in 4.0 at. % Tm,4.0 at. % Y：CaF2 single crystals under 792 nm laser diode（LD） pumping. The best laser performance has been demonstrated with a low threshold of 0.368 W, a high slope efficiency of 54.8%, and a maximum output power of 1.013 W.
