An LD directly-pumped solid-state laser is considered to be one of the most promising mid-infrared light sources because of its simple principle,small size,and compact structure for the generation of mid-infrared(MIR)...An LD directly-pumped solid-state laser is considered to be one of the most promising mid-infrared light sources because of its simple principle,small size,and compact structure for the generation of mid-infrared(MIR)lasers in the 3-5µm band.However,the quantum defect of LD directly-pumped MIR solid-state lasers will be much larger than that of ordinary near-infrared LD pumped solid-state lasers,which may lead to thermal damage and limit their development.In order to solve this problem,the methods of reducing the specific surface area of the crystal and improving the thermal energy released by the crystal structure are discussed,and the opti⁃mal length of the laser crystal is determined.The cooling structures of barium yttrium fluoride laser crystals(Ho^(3+):BY_(2)F_(8))of different lengths were studied by thermal simulation using COMSOL software.The experimen⁃tal results show that the output power can be increased and the thermal stress in the laser crystal can be alleviated by using the laser crystal whose length is slightly shorter than that of the cooler.The final experiment shows that when the pump repetition rate is 15 Hz and the pulse width is 90µs,the single pulse energy is 7.28 mJ at the out⁃put wavelength of 3.9µm,which is about 3 times as large as that of the crystal with the length of 10 mm(2.81 mJ).Such results should be another breakthrough of our team since the first directly-pumped solid-state MIR laser was realized more than a year ago.It might pave the way for the construction of a feasible MIR laser in the near future.展开更多
LNA is a new laser crystal discovered several years ago.The investigations have confirmed interest in LNA as a new,high-power,high-efficiency,solid-state neodymium laser.One of the advantages of LNA is the ability to ...LNA is a new laser crystal discovered several years ago.The investigations have confirmed interest in LNA as a new,high-power,high-efficiency,solid-state neodymium laser.One of the advantages of LNA is the ability to achieve a high Nd content,six times as high as that in YAG(2×10^(20)ions cm^(-3))without severe concentration quenching of the fluorescence and strong segregation of the dopingion along the laser rod.展开更多
The laset of Er^(3+)ion has had people’s attention because of its excellent properties and application.So we grew out crystal of ZnWO_(4):Er and measured its absorption,excitation and emission spectra.We can see from...The laset of Er^(3+)ion has had people’s attention because of its excellent properties and application.So we grew out crystal of ZnWO_(4):Er and measured its absorption,excitation and emission spectra.We can see from the absorption spectrum that the absorption of Erion in ZnWO_(4)crystal centers on two bands with peaks at 379nm and 522nm wavelength resPectively,for which the excitation light energy can be absorbed effectively.展开更多
The crystal of high concentration Nd:YAG was grown by flux method and diode pu mp microcavity laser was studied.High efficiency and frequency solid state lase r was built on research and development.some applications ...The crystal of high concentration Nd:YAG was grown by flux method and diode pu mp microcavity laser was studied.High efficiency and frequency solid state lase r was built on research and development.some applications such as target designa tion,laser radar,rangefinder,CATV etc. In order to maximize pump efficiency and power output,the Nd concentration shoul d be made as high as possible without degrading the gain through concentration q uenching.In crystal grown by Czochraski method.it is difficult to increase the N d concentration over 1.2% because of Nd segregation in the melt (yttrium aluminum garnet),which leads to large nonuniformities in doping.However,by using the f lux met hod growth technique,it is possible to grow uniformly doped crystal as much as 4 % Nd concentration YAG.展开更多
The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host...The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host material for solid state lasers.The threshold of the laser oscillations in a Nd 3+ d oped KGW laser crystal is considerable low and has a higher emissive section.T he fluorescent concentration quench effect of the Nd 3+ ion in the KGW crystal may be weakened due to the W O covalent bond,so this crystal has a higher dopi ng concentration of active ion.Furthermore,the absorption band at 808nm of Nd 3+ in the KGW crystal,which has 12nm FWHM,is well matched with the emission w avelength of a laser diode ,a solid state laser pump that is very convenient and popular in laser science and technology today.Therefore the KGW crystal has a l aser emission with higher output and higher efficiency.Scientists of laser techn ology circles are very interested in Yb 3+ doped laser crystals because they have four advanta ges when they are compared with Nd 3+ doped laser crystals.Firstly,their flu orescent lifetimes are three or four times as many as that of Nd 3+ doped la ser crystals,which is beneficial to reserving the energy.Secondly,the heat energ y,which is formed when laser is operating,will be decreased because the pumping band is close to the upper energy level.Not only will the use ratio of energy be increased but also the damage effect to laser properties will be decreased.Thir dly,there is no absorption problems of excite state because the energy level of Yb 3+ is simple.Finally,the higher optical quality crystals are easier to gr ow because the radius of Yb 3+ is closer to that of Gd 3+ .Furthermore,Y b 3+ doped laser crystals can substitute the Ti sapphire for the psec laser .展开更多
Red,blue and green visible lasers are more attractive with the development of the science and technology.Self frequency doubling is an important approach to realize visible lasers.For self frequency doubling,the basic...Red,blue and green visible lasers are more attractive with the development of the science and technology.Self frequency doubling is an important approach to realize visible lasers.For self frequency doubling,the basic requests are high figure of merit(FOM),high damage threshold,good chemical stability and mechanical properties.Perfection and growth characters are also important for a practical SFD crystal. In recent years,the discovery of rare earth calcium oxyborates has resulted in the renewal in the field of SFD crystal.ReCaO(BO 3) 3(ReCOB)is a new type of novel nonlinear optical crystals which is nearly congruently melt and can be grown with Czochralski method.ReCOB crystals possess high nonlinear coefficients and damage thresholds.They are non hydroscopic and easy cutting and polishing.They belong to monoclinic with point group m and space group cm.The strong anisotropy originated from the low symmetry makes the measurement and application of the crystal more complicated.More than half of naturally existed crystals belongs to low symmetry,consequently,the research on the nonlinear and anisotropic laser optical properties are not only important for ReCOB crystal,but also useful for the applications of other low symmetry crystals.展开更多
Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re...Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re∶GdYCOB single crystals growth were synthesized by multistage solid phase reaction method.Re∶GdYCOB single crystals were grown by Czochralski technique.The pulling rates are 0.5-2mm/h and the rotation rates are 10-30r/min.Usually 65-75% polycrystalline materials can be transformed into good quality single crystals under our growth conditions. The structures of some as grown Re∶GdYCOB single crystals were measured by using a four circle diffractometer.The results measured show that the space group of the crystals is C 3 s Cm.The determined lattice constants of 8 at% Nd doped Ca 4YO(BO 3) 3 single crystal are a =0.8076nm, b =1.6020nm, c =0.3527nm , β =101.23°.展开更多
The 3μm laser emission of Er 3+ ( 4 I 11/2 → 4 I 13/2 )in the YAG crystal is,in principle,selfsaturation transition,the lifetime of the upper laser level( 4 I 11/2 )being smaller than that of the olwer one( 4 I 13/2...The 3μm laser emission of Er 3+ ( 4 I 11/2 → 4 I 13/2 )in the YAG crystal is,in principle,selfsaturation transition,the lifetime of the upper laser level( 4 I 11/2 )being smaller than that of the olwer one( 4 I 13/2 ).The effect of the selfsaturation limit the laser output. In present work,for the first time,we report on the investigation of the utility of Pr 3+ as a sensitizer of Er 3+ ion,using Pr 3+ 4 f 2-4 f5d transition.The radiation emission from 4f5d configuration of Pr 3+ ion have been observed in the YAG∶Pr 3+ crystal.This shows that under suitable conditions this radiant process can compete successfully by non radiative decay to the 4 f configuration.Using Er 3+ Pr 3 codoped YAG it is possible to predict the position of the lowest 4 f 2-4 f5d absorption bands of Pr 3+ ion in the ultraviolet range and to present the occurrence of the energy transfer from Pr 3+ to Er 3+ ion.By xenon flash lamp pumped 2.93μm laser action in the YAG∶(Er 3+ ,Pr 3+ ) crystals was demonstrated at room temperature.展开更多
Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable r...Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable range and their impressive feature of narrow linewidth make these solid state lasers important to molecular spectroscopy,pollution detection,fiber optics communication and other scientific research fields.The( F + 2) H center consisting of an F + 2 center and an neibouring O 2- ion,is one of the most important color centers.In this paper,we will study the preparation,absorption and emission spectra of the ( F + 2) H center in mixed crystal KCl KBr∶OH -. Single crystals of KCl,KBr and different compositions of KCl x Br 1-x solid solutions are growtn with 0.1mol%—0.3mol% KOH in the melt by the Czochralski technique in air.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
In recent years,from the laser experimental study of neodymium doped potassium g adolinium tungstate,i.e.KGd(WO 4) 2 (KGW),laser scientific workers had discove r ed that it has many advantages,as compared to YAG and o...In recent years,from the laser experimental study of neodymium doped potassium g adolinium tungstate,i.e.KGd(WO 4) 2 (KGW),laser scientific workers had discove r ed that it has many advantages,as compared to YAG and other tungstate crystals u n der indentical experimental conditions,such as low lasing threshold,high output energy o r power and high efficiency et al.Especially,as seen on the absorption spectra o f Nd:YAG and Nd:KGW reported by V.Kushawaha et al,a strong and broad absorption line around 808nm is much wider (～12nmFWHM) in Nd:KGW as compared to the Nd:YAG (～1.5nm FWHM),and this wavelength is just during the main peak area emitted by diode laser,so that Nd:KGW may be a excellent candidate for efficient diode pum ping at 808nm.Therefore the research and development of KGW crystals and laser d evices has been bestowed great attention in interational laser science area.For the laser rod with dimensions of 5mm×8mm and 6.3mm×75mm,the xenon flashlamp pumping KGW laser have achieved more laser output and higher efficie n ies than the YAG crystals under identical experimental conditions,by V.Kushawaha et al.In Unite State and K.A.Stankov et al.in Germang respectively.展开更多
With the development of the diode laser pump sources,the Yb 3+ doped crystals have brought much attention which is not suitable for flash light pump source since they are not match in spectrum region.Comparing with Nd...With the development of the diode laser pump sources,the Yb 3+ doped crystals have brought much attention which is not suitable for flash light pump source since they are not match in spectrum region.Comparing with Nd 3+ doped crystals,Yb 3+ doped crystals have many advantages,for example, (1)Yb 3+ doped crystals have very low thermal load,(only about 1/3 of that of Nd 3+ doped crystals) therefore,the systems can obtain lasers with higher optical quality and higher average power. (2)The energy stored up ability of Yb 3+ doped crystals is about 5 times as much as that of Nd 3+ doped crystals. (3)The position of main absorption peak of Yb 3+ matches to the pumping InGaAs diode emission,which is more durable than the AlGaAs diode used to pump the Nd 3+ . (4)The full width at half maximum of Yb 3+ doped crystals is 10 times as much as that of Nd 3+ doped crystals,so,the temperature control requirement of laser diode is relatively moderate. (5)From the point of view of energy transfer,because of the inherently small quantum defect of the Yb 3+ ,the theoredtical quantum efficiency can get up to 91%.展开更多
After 40 years of development,laser crystals have established a firm foundation for solid state laser technology.The improvements of the crystals now on hand and the exploration of new crystals are still going on acti...After 40 years of development,laser crystals have established a firm foundation for solid state laser technology.The improvements of the crystals now on hand and the exploration of new crystals are still going on actively. 1 Development of the laser crystals now on hand 1.1 YAG YAG is a laser crystal with good property,extensive application and wide scale manufacturing.Aimed at the need of LD pumping,many new varieties of garnet have been developed,with the goal of enlarging the absorption of line width.The idea of this development is chiefly as the follows:(1)Enlarge the lattice constant through substitution of cations;(2)Waiden the absorption spectrum through the vacancy of cations;(3)Using cations with host sensitization,such as Mn 2+ ,etc.The author has considered several optional varieties:Y 2.7 La 0.25 Nd 0.05 Al 3.5 Nb 0.9 O 12 (calculating lattice constant: a 0～1.202nm,in contrast of that of YAG: a 0～1.200nm);Y 1.5 LaMn 2+ 0.5 Al 4.5 Si 0.5 O 12 ( a 0～1.205nm);and YLaMn 2+ Al 4(Nb,V) 5+ 0.6 O 12 ( a 0～1.204nm);etc.展开更多
NaCl(OH^(-)):(F_(2)^(+))is a color center laser crystaJ with best laser performance and imPortant applications at Present.We have succeeded in develoPing this crystal and realizing its laser operation.For raising the ...NaCl(OH^(-)):(F_(2)^(+))is a color center laser crystaJ with best laser performance and imPortant applications at Present.We have succeeded in develoPing this crystal and realizing its laser operation.For raising the concentration and the stability of(F_(2)^(+))center,we have studied its route of formation,state,and control of conditions,with fairly good results as follows:The doping of OH facilitates the formation of high-order aggregated center in crystal during co-loration.展开更多
Titanium-doped sapphire is a phonon-terminated laser crystal which is applied in many fields. But residual infrared absorption in laser operation region of the crystal hindered the improvement of the crystal quality.T...Titanium-doped sapphire is a phonon-terminated laser crystal which is applied in many fields. But residual infrared absorption in laser operation region of the crystal hindered the improvement of the crystal quality.The macroscopic defects in the crystal often perplexed growers.展开更多
Titanium-doped sapphire is an excellent laser crystal which has a bright future.But the residual infrared absorption in laser operation region of the crystal hindered the enhancement of the laser gain.Reducing the res...Titanium-doped sapphire is an excellent laser crystal which has a bright future.But the residual infrared absorption in laser operation region of the crystal hindered the enhancement of the laser gain.Reducing the residual infrared absorption is the key to that the crystal goes from experimental prototypesto commercially available products.展开更多
基金Supported by the National Key Research and Development Program of China(2021YFA0718803)。
文摘An LD directly-pumped solid-state laser is considered to be one of the most promising mid-infrared light sources because of its simple principle,small size,and compact structure for the generation of mid-infrared(MIR)lasers in the 3-5µm band.However,the quantum defect of LD directly-pumped MIR solid-state lasers will be much larger than that of ordinary near-infrared LD pumped solid-state lasers,which may lead to thermal damage and limit their development.In order to solve this problem,the methods of reducing the specific surface area of the crystal and improving the thermal energy released by the crystal structure are discussed,and the opti⁃mal length of the laser crystal is determined.The cooling structures of barium yttrium fluoride laser crystals(Ho^(3+):BY_(2)F_(8))of different lengths were studied by thermal simulation using COMSOL software.The experimen⁃tal results show that the output power can be increased and the thermal stress in the laser crystal can be alleviated by using the laser crystal whose length is slightly shorter than that of the cooler.The final experiment shows that when the pump repetition rate is 15 Hz and the pulse width is 90µs,the single pulse energy is 7.28 mJ at the out⁃put wavelength of 3.9µm,which is about 3 times as large as that of the crystal with the length of 10 mm(2.81 mJ).Such results should be another breakthrough of our team since the first directly-pumped solid-state MIR laser was realized more than a year ago.It might pave the way for the construction of a feasible MIR laser in the near future.
文摘LNA is a new laser crystal discovered several years ago.The investigations have confirmed interest in LNA as a new,high-power,high-efficiency,solid-state neodymium laser.One of the advantages of LNA is the ability to achieve a high Nd content,six times as high as that in YAG(2×10^(20)ions cm^(-3))without severe concentration quenching of the fluorescence and strong segregation of the dopingion along the laser rod.
文摘The laset of Er^(3+)ion has had people’s attention because of its excellent properties and application.So we grew out crystal of ZnWO_(4):Er and measured its absorption,excitation and emission spectra.We can see from the absorption spectrum that the absorption of Erion in ZnWO_(4)crystal centers on two bands with peaks at 379nm and 522nm wavelength resPectively,for which the excitation light energy can be absorbed effectively.
文摘The crystal of high concentration Nd:YAG was grown by flux method and diode pu mp microcavity laser was studied.High efficiency and frequency solid state lase r was built on research and development.some applications such as target designa tion,laser radar,rangefinder,CATV etc. In order to maximize pump efficiency and power output,the Nd concentration shoul d be made as high as possible without degrading the gain through concentration q uenching.In crystal grown by Czochraski method.it is difficult to increase the N d concentration over 1.2% because of Nd segregation in the melt (yttrium aluminum garnet),which leads to large nonuniformities in doping.However,by using the f lux met hod growth technique,it is possible to grow uniformly doped crystal as much as 4 % Nd concentration YAG.
文摘The KGd(WO 4) 2[KGW] crystal has a structure belonging to the monoclinic sys tem with space group C 2/ c and with unit cell dimensions a =1.068mm, b =1.043nm, c =0.76nm, β =130°.This crystal is an excellent host material for solid state lasers.The threshold of the laser oscillations in a Nd 3+ d oped KGW laser crystal is considerable low and has a higher emissive section.T he fluorescent concentration quench effect of the Nd 3+ ion in the KGW crystal may be weakened due to the W O covalent bond,so this crystal has a higher dopi ng concentration of active ion.Furthermore,the absorption band at 808nm of Nd 3+ in the KGW crystal,which has 12nm FWHM,is well matched with the emission w avelength of a laser diode ,a solid state laser pump that is very convenient and popular in laser science and technology today.Therefore the KGW crystal has a l aser emission with higher output and higher efficiency.Scientists of laser techn ology circles are very interested in Yb 3+ doped laser crystals because they have four advanta ges when they are compared with Nd 3+ doped laser crystals.Firstly,their flu orescent lifetimes are three or four times as many as that of Nd 3+ doped la ser crystals,which is beneficial to reserving the energy.Secondly,the heat energ y,which is formed when laser is operating,will be decreased because the pumping band is close to the upper energy level.Not only will the use ratio of energy be increased but also the damage effect to laser properties will be decreased.Thir dly,there is no absorption problems of excite state because the energy level of Yb 3+ is simple.Finally,the higher optical quality crystals are easier to gr ow because the radius of Yb 3+ is closer to that of Gd 3+ .Furthermore,Y b 3+ doped laser crystals can substitute the Ti sapphire for the psec laser .
文摘Red,blue and green visible lasers are more attractive with the development of the science and technology.Self frequency doubling is an important approach to realize visible lasers.For self frequency doubling,the basic requests are high figure of merit(FOM),high damage threshold,good chemical stability and mechanical properties.Perfection and growth characters are also important for a practical SFD crystal. In recent years,the discovery of rare earth calcium oxyborates has resulted in the renewal in the field of SFD crystal.ReCaO(BO 3) 3(ReCOB)is a new type of novel nonlinear optical crystals which is nearly congruently melt and can be grown with Czochralski method.ReCOB crystals possess high nonlinear coefficients and damage thresholds.They are non hydroscopic and easy cutting and polishing.They belong to monoclinic with point group m and space group cm.The strong anisotropy originated from the low symmetry makes the measurement and application of the crystal more complicated.More than half of naturally existed crystals belongs to low symmetry,consequently,the research on the nonlinear and anisotropic laser optical properties are not only important for ReCOB crystal,but also useful for the applications of other low symmetry crystals.
文摘Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re∶GdYCOB single crystals growth were synthesized by multistage solid phase reaction method.Re∶GdYCOB single crystals were grown by Czochralski technique.The pulling rates are 0.5-2mm/h and the rotation rates are 10-30r/min.Usually 65-75% polycrystalline materials can be transformed into good quality single crystals under our growth conditions. The structures of some as grown Re∶GdYCOB single crystals were measured by using a four circle diffractometer.The results measured show that the space group of the crystals is C 3 s Cm.The determined lattice constants of 8 at% Nd doped Ca 4YO(BO 3) 3 single crystal are a =0.8076nm, b =1.6020nm, c =0.3527nm , β =101.23°.
文摘The 3μm laser emission of Er 3+ ( 4 I 11/2 → 4 I 13/2 )in the YAG crystal is,in principle,selfsaturation transition,the lifetime of the upper laser level( 4 I 11/2 )being smaller than that of the olwer one( 4 I 13/2 ).The effect of the selfsaturation limit the laser output. In present work,for the first time,we report on the investigation of the utility of Pr 3+ as a sensitizer of Er 3+ ion,using Pr 3+ 4 f 2-4 f5d transition.The radiation emission from 4f5d configuration of Pr 3+ ion have been observed in the YAG∶Pr 3+ crystal.This shows that under suitable conditions this radiant process can compete successfully by non radiative decay to the 4 f configuration.Using Er 3+ Pr 3 codoped YAG it is possible to predict the position of the lowest 4 f 2-4 f5d absorption bands of Pr 3+ ion in the ultraviolet range and to present the occurrence of the energy transfer from Pr 3+ to Er 3+ ion.By xenon flash lamp pumped 2.93μm laser action in the YAG∶(Er 3+ ,Pr 3+ ) crystals was demonstrated at room temperature.
文摘Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable range and their impressive feature of narrow linewidth make these solid state lasers important to molecular spectroscopy,pollution detection,fiber optics communication and other scientific research fields.The( F + 2) H center consisting of an F + 2 center and an neibouring O 2- ion,is one of the most important color centers.In this paper,we will study the preparation,absorption and emission spectra of the ( F + 2) H center in mixed crystal KCl KBr∶OH -. Single crystals of KCl,KBr and different compositions of KCl x Br 1-x solid solutions are growtn with 0.1mol%—0.3mol% KOH in the melt by the Czochralski technique in air.
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.
文摘In recent years,from the laser experimental study of neodymium doped potassium g adolinium tungstate,i.e.KGd(WO 4) 2 (KGW),laser scientific workers had discove r ed that it has many advantages,as compared to YAG and other tungstate crystals u n der indentical experimental conditions,such as low lasing threshold,high output energy o r power and high efficiency et al.Especially,as seen on the absorption spectra o f Nd:YAG and Nd:KGW reported by V.Kushawaha et al,a strong and broad absorption line around 808nm is much wider (～12nmFWHM) in Nd:KGW as compared to the Nd:YAG (～1.5nm FWHM),and this wavelength is just during the main peak area emitted by diode laser,so that Nd:KGW may be a excellent candidate for efficient diode pum ping at 808nm.Therefore the research and development of KGW crystals and laser d evices has been bestowed great attention in interational laser science area.For the laser rod with dimensions of 5mm×8mm and 6.3mm×75mm,the xenon flashlamp pumping KGW laser have achieved more laser output and higher efficie n ies than the YAG crystals under identical experimental conditions,by V.Kushawaha et al.In Unite State and K.A.Stankov et al.in Germang respectively.
文摘With the development of the diode laser pump sources,the Yb 3+ doped crystals have brought much attention which is not suitable for flash light pump source since they are not match in spectrum region.Comparing with Nd 3+ doped crystals,Yb 3+ doped crystals have many advantages,for example, (1)Yb 3+ doped crystals have very low thermal load,(only about 1/3 of that of Nd 3+ doped crystals) therefore,the systems can obtain lasers with higher optical quality and higher average power. (2)The energy stored up ability of Yb 3+ doped crystals is about 5 times as much as that of Nd 3+ doped crystals. (3)The position of main absorption peak of Yb 3+ matches to the pumping InGaAs diode emission,which is more durable than the AlGaAs diode used to pump the Nd 3+ . (4)The full width at half maximum of Yb 3+ doped crystals is 10 times as much as that of Nd 3+ doped crystals,so,the temperature control requirement of laser diode is relatively moderate. (5)From the point of view of energy transfer,because of the inherently small quantum defect of the Yb 3+ ,the theoredtical quantum efficiency can get up to 91%.
文摘After 40 years of development,laser crystals have established a firm foundation for solid state laser technology.The improvements of the crystals now on hand and the exploration of new crystals are still going on actively. 1 Development of the laser crystals now on hand 1.1 YAG YAG is a laser crystal with good property,extensive application and wide scale manufacturing.Aimed at the need of LD pumping,many new varieties of garnet have been developed,with the goal of enlarging the absorption of line width.The idea of this development is chiefly as the follows:(1)Enlarge the lattice constant through substitution of cations;(2)Waiden the absorption spectrum through the vacancy of cations;(3)Using cations with host sensitization,such as Mn 2+ ,etc.The author has considered several optional varieties:Y 2.7 La 0.25 Nd 0.05 Al 3.5 Nb 0.9 O 12 (calculating lattice constant: a 0～1.202nm,in contrast of that of YAG: a 0～1.200nm);Y 1.5 LaMn 2+ 0.5 Al 4.5 Si 0.5 O 12 ( a 0～1.205nm);and YLaMn 2+ Al 4(Nb,V) 5+ 0.6 O 12 ( a 0～1.204nm);etc.
文摘NaCl(OH^(-)):(F_(2)^(+))is a color center laser crystaJ with best laser performance and imPortant applications at Present.We have succeeded in develoPing this crystal and realizing its laser operation.For raising the concentration and the stability of(F_(2)^(+))center,we have studied its route of formation,state,and control of conditions,with fairly good results as follows:The doping of OH facilitates the formation of high-order aggregated center in crystal during co-loration.
文摘Titanium-doped sapphire is a phonon-terminated laser crystal which is applied in many fields. But residual infrared absorption in laser operation region of the crystal hindered the improvement of the crystal quality.The macroscopic defects in the crystal often perplexed growers.
文摘Titanium-doped sapphire is an excellent laser crystal which has a bright future.But the residual infrared absorption in laser operation region of the crystal hindered the enhancement of the laser gain.Reducing the residual infrared absorption is the key to that the crystal goes from experimental prototypesto commercially available products.
