In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power a...In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power at high injection currents.In this paper,a simplified numerical analysis model is proposed for 1.06μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional(1D)rate equations.The ef⁃fects of LSHB,TPA and FCA on the output characteristics are systematically analyzed,and it is proposed that ad⁃justing the front facet reflectivity and the position of the quantum well(QW)in the waveguide layer can improve the front facet output power.展开更多
The dissolved gas analysis is one of the most effective and convenient methods to diagnose the early discharge faults of transformers,the fault involves the solid insulation.oil—paper insulation cracks and releases c...The dissolved gas analysis is one of the most effective and convenient methods to diagnose the early discharge faults of transformers,the fault involves the solid insulation.oil—paper insulation cracks and releases carbon monoxide(co)gas.Therefore,the detection of CO can forecast the potentia1 inner faults of oil.filled transformers.展开更多
There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresse...There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.展开更多
Beam shaping is required for semiconductor lasers to achieve high optical fiber coupling efficiency in many applications.But the positioning errors on optics may reduce beam shaping effects,and then lead to low optica...Beam shaping is required for semiconductor lasers to achieve high optical fiber coupling efficiency in many applications.But the positioning errors on optics may reduce beam shaping effects,and then lead to low optical fiber coupling efficiency.In this work,the positioning errors models for the single emitter laser diode beam shaping system are established.Moreover,the relationships between the errors and the beam shaping effect of each shapers are analysed.Subsequently,the relationship between the errors and the optical fiber coupling efficiency is analysed.The result shows that position errors in the Z axis direction on the fast axis collimator have the greatest influence on the shaping effect,followed by the position errors in the Z axis direction on the converging lens,which should be strictly suppressed in actual operation.Besides,the position errors have a significant influence on the optical fiber coupling efficiency and need to be avoided.展开更多
A novel and efficient absorption line recovery technique is presented.A micro-electromechanical systems(MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirr...A novel and efficient absorption line recovery technique is presented.A micro-electromechanical systems(MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirror reflection.Tunable diode laser spectroscopy(TDLS) and photoacoustic spectroscopy(PAS) are used to recover the target absorption line profile which is compared with the theoretical Voigt profile.The target gas is 0.01% acetylene(C2H2) in a nitrogen host gas.The laser diode wavelength is swept across the P17 absorption line of acetylene at 1 535.4 nm by a current ramp,and an erbium-doped fibre amplifier(EDFA) is used to enhance the optical intensity and increase the signal-to-noise ratio(SNR).A SNR of about 35 is obtained with 100 mW laser power from the EDFA.Good agreement is achieved between the experimental results and the theoretical simulation for the P17 absorption line profile.展开更多
Starting from the data obtained recently,that the crystal yttrium aluminum borat e(NAB)is an ideal material for LD pumped microchip laser is demonstrated.Coopera ting with Material Physics Department of Autonoma Unive...Starting from the data obtained recently,that the crystal yttrium aluminum borat e(NAB)is an ideal material for LD pumped microchip laser is demonstrated.Coopera ting with Material Physics Department of Autonoma University of Madrid,Ti:sappir e laser was used to simulate laser diode to pump a NAB crystal sample of 0.3mm t hickness.For incident pump power of 375mW,laser output power at 1.064μm reach 1 57mW with optical to optical efficiency as high as 42%.The corresponding effici e ncy at 1.341μm is 25%.Output laser beams belong to TEM 00 mode.The thresho ld of laser oscillation at 1.064μm were 13,18,30,100 and 140mW for output mirr ors with transmittance of 0.36%,1%,2%,4% and 6% respectively.NAB crystal has a wide and flat absorption band with half high width of 45nm for pump light and so th e temperature shift of the laser diode wavelength will not affect the pumping effi ciency.All the advantages mentioned show the this crystal is obviously an ideal material for LD pumped microchip laser. Therefrom,the possible application of a series of self ativated laser crystal developed in the seventies years 20th century will be discussed in the case of L D lasers have been well developed.展开更多
基金Supported by National Key R&D Project(2017YFB0405100)National Natural Science Foundation of China(61774024/61964007)Jilin province science and technology development plan(20190302007GX)。
文摘In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power at high injection currents.In this paper,a simplified numerical analysis model is proposed for 1.06μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional(1D)rate equations.The ef⁃fects of LSHB,TPA and FCA on the output characteristics are systematically analyzed,and it is proposed that ad⁃justing the front facet reflectivity and the position of the quantum well(QW)in the waveguide layer can improve the front facet output power.
文摘The dissolved gas analysis is one of the most effective and convenient methods to diagnose the early discharge faults of transformers,the fault involves the solid insulation.oil—paper insulation cracks and releases carbon monoxide(co)gas.Therefore,the detection of CO can forecast the potentia1 inner faults of oil.filled transformers.
文摘There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.
基金Project(51475479) supported by the National Natural Science Foundation of ChinaProject(2017YFB1104800) supported by the National Key Research and Development Program of China+2 种基金Project(2016GK2098) supported by the Key Research and Development Program of Hunan Province,ChinaProject(ZZYJKT2017-07) supported by the State Key Laboratory of High Performance Complex Manufacturing,Central South University,ChinaProject(JMTZ201804) supported by the Key Laboratory for Precision&Non-traditional Machining of Ministry of Education,Dalian University of Technology,China
文摘Beam shaping is required for semiconductor lasers to achieve high optical fiber coupling efficiency in many applications.But the positioning errors on optics may reduce beam shaping effects,and then lead to low optical fiber coupling efficiency.In this work,the positioning errors models for the single emitter laser diode beam shaping system are established.Moreover,the relationships between the errors and the beam shaping effect of each shapers are analysed.Subsequently,the relationship between the errors and the optical fiber coupling efficiency is analysed.The result shows that position errors in the Z axis direction on the fast axis collimator have the greatest influence on the shaping effect,followed by the position errors in the Z axis direction on the converging lens,which should be strictly suppressed in actual operation.Besides,the position errors have a significant influence on the optical fiber coupling efficiency and need to be avoided.
基金Financial support from National High Technology Research and Development Programof China(Grant No.:2007A A06Z1122007AA03Z446)
文摘A novel and efficient absorption line recovery technique is presented.A micro-electromechanical systems(MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirror reflection.Tunable diode laser spectroscopy(TDLS) and photoacoustic spectroscopy(PAS) are used to recover the target absorption line profile which is compared with the theoretical Voigt profile.The target gas is 0.01% acetylene(C2H2) in a nitrogen host gas.The laser diode wavelength is swept across the P17 absorption line of acetylene at 1 535.4 nm by a current ramp,and an erbium-doped fibre amplifier(EDFA) is used to enhance the optical intensity and increase the signal-to-noise ratio(SNR).A SNR of about 35 is obtained with 100 mW laser power from the EDFA.Good agreement is achieved between the experimental results and the theoretical simulation for the P17 absorption line profile.
文摘Starting from the data obtained recently,that the crystal yttrium aluminum borat e(NAB)is an ideal material for LD pumped microchip laser is demonstrated.Coopera ting with Material Physics Department of Autonoma University of Madrid,Ti:sappir e laser was used to simulate laser diode to pump a NAB crystal sample of 0.3mm t hickness.For incident pump power of 375mW,laser output power at 1.064μm reach 1 57mW with optical to optical efficiency as high as 42%.The corresponding effici e ncy at 1.341μm is 25%.Output laser beams belong to TEM 00 mode.The thresho ld of laser oscillation at 1.064μm were 13,18,30,100 and 140mW for output mirr ors with transmittance of 0.36%,1%,2%,4% and 6% respectively.NAB crystal has a wide and flat absorption band with half high width of 45nm for pump light and so th e temperature shift of the laser diode wavelength will not affect the pumping effi ciency.All the advantages mentioned show the this crystal is obviously an ideal material for LD pumped microchip laser. Therefrom,the possible application of a series of self ativated laser crystal developed in the seventies years 20th century will be discussed in the case of L D lasers have been well developed.
