Nd-doped low temperature phase lanthanum-scandium borate self-frequency doubling laser crystal
The invention belongs to the photoelectron material technical field, particularly relate to self-frequency doubling laser crystal as the working-laser material in the solid laser.
Frequency multiplication is a kind of method that changes the laser beam output wavelength of often using in the laser technology.It adopts a special non-linear optic crystal usually, places the laser beam front to change the laser beam output wavelength.Laser generation and two kinds of technology of frequency multiplication effect can be concentrated on the same crystal, obtain self-frequency-doubling laser? people such as sixties Johnson are mixing Tm
3+LiNbO
3On the same crystal, realized 1853 millimicrons to 927 millimicrons self-frequency-doubling laser output, but efficiency of conversion only reaches the 10-6 order of magnitude (L.F.Johnson and A.A.Ballman, J.Appl.Phys., 40 (1969) 297).People such as sieve degree of abiding by in 1989 work out the NYAB crystal of high conversion efficiency, obtain 532 millimicrons green self-frequency-doubling laser (Luo Zundu (Luo Zundu), Jiang Aidong (Jiang Aidong), Huang Yichuan (Huang Yichuan), Qiu Minwang (Qiu Minwang), Chinese Phys.Lett., 6 (1989) 440).But because the crystal mass problem that the crystal self-defect causes does not have practical application so far.The Nd of neodymium-doped
3+: LaSc
3(BO
3)
4Be a kind of laser crystal material, LaSc
3(BO
3)
4Crystal has multiple different phase structure, i.e. C2/c spacer (belonging to the high temperature phase) and R32 spacer structure (belonging to low temperature mutually).Nd with neodymium-doped of C2/c spacer
3+: LaSc
3(BO
3)
4Laser crystal material as the LD pumping is reported (J-P.Meyn, T.Jensen, G.Huber, IEEE J.Quantum Electronics, 30 (1994) 913) by the people such as J-P.Meyn of Germany.Although they point out, be higher than the Nd:LaSc of 50at.% in neodymium ion concentration
3(BO
3)
4Crystal belong to the R32 spacer, and observe frequency-doubled effect, but really do not obtain self-frequency-doubling laser.And they can only adopt the crystal pulling method technology growth to go out the Nd that neodymium ion concentration is higher than 50at.%
3+: LaSc
3(BO
3)
4Crystal, can't grow neodymium ion and be lower than 50at.%'s and Nd with R32 spacer structure
3+: LaSc
3(BO
3)
4Crystal.In fact, the Nd that is higher than 50at.% in neodymium ion concentration
3+: LaSc
3(BO
3)
4Crystal in be the self-frequency-doubling laser that can't obtain high conversion efficiency.Because neodymium ion (Nd
3+) light of 550 millimicrons of wavelength there is very big absorptivity, neodymium ion concentration is high more, absorbs serious more.532 millimicrons green laser will be absorbed most ofly in the self-frequency doubling laser crystal of mixing high neodymium ion concentration so.
Purpose of the present invention just is to develop the class low temperature phase Nd of the neodymium-doped of a kind of high conversion efficiency LD pumping for scandium
3+: LaSc
3-xM
x(BO
3)
4(M=Al or Ga; 2.5 〉=x 〉=0) new green self-frequency doubling laser crystal.
Nd of the present invention
3+: LaSc
3(BO
3)
4Crystal belongs to the low temperature phase, and Nd ion doped concentration has R32 spacer structure, and has non-linear optical effect, and can be used as self-frequency doubling laser crystal between lat.%~25at.%.
Nd of the present invention
3+: LaSc
3(BO
3)
4Crystal belongs to the low temperature phase, and Nd ion doped concentration has Cc spacer structure, and has non-linear optical effect, and can be used as self-frequency doubling laser crystal between lat.%~25at.%.
The present invention uses a kind of composite fluxing agent Li
2O-B
2O
3-LiF, ratio is (1~4): (3~1): (0.1~3) molecular ratio, that adopts that case of flux methods can grow that neodymium ion concentration is lower than 50at% has a R32 spacer structure low temperature phase Nd
3+: LaSc
3(BO
3)
4Fusing assistant Li in the growth
2O-B
2O
3-LiF concentration is controlled between 25wt.%~65wt.%.In growth temperature is controlled at 1300 ℃~1050 ℃ scopes, adopt 2~5 ℃/day rate of temperature fall and 4~50 rev/mins crystal rotating speed, grow and have R32 spacer structure low temperature phase Nd
3+: LaSc
3(BO
3)
4Crystal (seeing embodiment 1).
The present invention uses a kind of composite fluxing agent Li
2O-B
2O
3-LiF, ratio is (1-4): (3~1): (0.1~3) molecular ratio, that adopts that case of flux methods can grow that neodymium ion concentration is lower than 50at% has a Cc spacer structure low temperature phase Nd
3+: LaSc
3(BO
3)
4Fusing assistant Li in the growth
2O-B
2O
3-LiF concentration is controlled between 25wt.%~65wt.%.In growth temperature is controlled at 1050~850 ℃ of scopes, adopt 2~5 ℃/day rate of temperature fall and 4~50 rev/mins crystal rotating speed, grow and have Cc spacer structure low temperature phase Nd
3+: LaSc
3(BO
3)
4Crystal (seeing embodiment 2).
R32 spacer structure and the low temperature with Cc spacer structure Nd mutually will be had
3+: LaSc
3(BO
3)
4Obtain self-frequency-doubling laser in the crystal, neodymium ion concentration can not be higher than 50at%.Low temperature phase Nd in this research
3+: LaSc
3(BO
3)
4In the crystal, neodymium ion concentration is controlled between 1at.%~25at.%.Although low temperature phase Nd
3+: LaSc
3(BO
3)
4Crystalline structure has the neodymium ion laser neodymium ion that can mix higher concentration, and has only the characteristics (seeing Fig. 1,2) of very low fluorescence concentration quenching effect.But for this neodymium-doped self-frequency doubling laser crystal with complex function, hope has higher neodymium ion concentration to be beneficial to increase the luminous number of crystal unit volume in laser crystals, thereby improve gain of crystalline fundamental wave of laser and light intensity, reach higher frequency-doubling conversion efficiency and second harmonic laser energy output.But neodymium ion has very big absorptivity to the light of 550 millimicrons of wavelength, loss the second harmonic light output intensity.Neodymium ion concentration is high more, absorbs seriously more, and the second harmonic optical loss is big more.Low temperature phase Nd
3+: LaSc
3(BO
3)
4532 millimicrons of green lasers that crystal produced will be absorbed most ofly.To obtain high conversion efficiency at self-frequency doubling laser crystal, must the suitable neodymium ion concentration of control in crystal.In the research in the crystal neodymium ion concentration should remain between the 1at.% to 25at.%.Reach and both improve Nd
3+: LaSc
3(BO
3)
4Fundamental wave of laser gains and light intensity in the crystal, can obtain the self-frequency-doubling laser of higher frequency-doubling conversion efficiency and second harmonic laser energy output again.Low temperature phase Nd
3+: LaSc
3(BO
3)
4Crystal is 3.3 millimicrons in the peak width at half height (FWHM) of 810 millimicrons of absorption peaks, is 4 times, the Nd:YVO of Nd:YAG
41.6 times of (see figure 3)s.The strongest fluorescent emission wavelength is 1063 millimicrons, and to have big emission transition cross section be 46 * 10
-20Cm
2, fluorescence lifetime is 112 μ s (see figure 4)s.The product (1.7 * 10 of its emission transition cross section and fluorescence lifetime
-23Cm
2S) be 3 times of NYAB.Because the absorption peak of broad helps the absorption of laser crystals to pump light, improved output rating.Life-span, long crystal can accumulate more particle at last energy level, had increased energy storage, helped the raising of device output rating and energy.The long-pending big crystal of σ and τ σ is realized laser generation easily, can obtain bigger output under identical power input.So low temperature phase Nd of neodymium-doped
3+: LaSc
3(BO
3)
4Crystal is a kind of self-frequency doubling laser crystal with high conversion efficiency, low cost, high optical quality and actual use value.
Because Nd
3+: LaSc
3(BO
3)
4Scium trioxide is very expensive in the crystal, and the present invention uses, and aluminum oxide cheap, that thermal conductance is good substitutes Scium trioxide partly, adopts Li
2O-B
2O
3-LiF fusing assistant, ratio are (1~4): (3~1): (0.1~3) molecular ratio grows neodymium-doped lanthanum aluminium scandium crystal (Nd
3+: LaSc
3-xAl
x(BO
3)
4) (seeing embodiment 3).Neodymium ion concentration in the boric acid lanthanum aluminium scandium crystal is controlled between the 1at.% to 25at.%.Under the growing environment of 1300~1050 ° of temperature, grow Nd with R32 spacer
3+: LaSc
3-xAl
x(BO
3)
4Crystal.Under the growing environment of 1050~850 ° of temperature, grow Nd with Cc spacer
3+: LaSc
3-xAl
x(BO
3)
4Crystal.Make Nd
3+: LaSc
3-xAl
x(BO
3)
4Crystal had both kept the low temperature phase Nd of original neodymium-doped
3+: LaSc
3(BO
3)
4Crystalline structural performance and laser activity have high conversion efficiency, low cost, high optical quality again.
Equally, use gallium oxide to substitute the Scium trioxide of part, adopt Li
2O-B
2O
3-LiF fusing assistant, ratio are (1~4): (3~1): (0.1~3) molecular ratio, adopt case of flux methods to grow neodymium-doped lanthanum gallium scandium (Nd
3+: LaSc
3-xGa
x(BO
3)
4) (embodiment 4) crystal, the neodymium ion concentration in the neodymium-doped lanthanum gallium scandium crystal is controlled between the 1at.% to 25at.%.Under the growing environment of 1300~1050 ° of temperature, grow Nd with R32 spacer
3+: LaSc
3-xGa
x(BO
3)
4Crystal.Under the growing environment of 1050~850 ° of temperature, grow Nd with Cc spacer
3+: LaSc
3-xGa
x(BO
3)
4Crystal.The same low temperature phase Nd that obtains to keep original neodymium-doped
3+: LaSc
3(BO
3)
4The self-frequency doubling laser crystal of crystalline structural performance and laser activity.
The present invention is different with the Czochralski grown technological method that other people adopt, and adopts case of flux methods and a kind of composite fluxing agent Li
2O-B
2O
3-LiF, ratio is (1~4): (3~1): (0.1~3) molecular ratio can grow the low temperature phase Nd that neodymium ion concentration is lower than the 50at.% neodymium-doped
3+: LaSc
3(BO
3)
4Crystal.Adopt compounds such as the aluminum oxide cheap, that thermal conductance is good, gallium oxide partly to substitute expensive Scium trioxide simultaneously, grow Nd with low temperature phase structure
3+: LaSc
3-xAl
x(BO
3)
4And Nd
3+: LaSc
3-xGa
x(BO
3)
4New self-frequency doubling laser crystal.Feasible Nd with low temperature phase structure
3+: LaSc
3-xAl
x(BO
3)
4And Nd
3+: LaSc
3-xGa
x(BO
3)
4Crystal had both kept former low temperature phase Nd
3+: LaSc
3(BO
3)
4Crystalline structural performance and laser activity, the green self-frequency doubling laser crystal that has high conversion efficiency, low cost, high optical quality and actual use value again.Green self-frequency-doubling laser can be applicable to typing, the storage of information in the high density compact disc and shows that now multicolor printing is in the technology such as compact disc.
Fig. 1 is the low temperature phase Nd with R32 spacer structure
3+: LaSc
3(BO
3)
4Crystalline structure figure.It is by a cover LaO
6Distorted octahedra, a cover ScO
6Distorted octahedra and two cover BO
3Plane triangle is formed.Each Sc ion and six oxonium ions form ScO
6Distorted octahedra.Each La ion and six oxonium ions form LaO
6Distorted octahedra.Work as Nd
3+Mix LaSc
3(BO
3)
4During crystal, it occupies the La ion position.Each LaO
6Distorted octahedra does not have the common oxonium ion, couples together LaO by La (Nd)-O-Sc (O)-O-La (Nd) chain
6Isolated each other between the distorted octahedra.Shortest distance is 6.263 between La (Nd)-La (Nd).In having the crystal of this structure, when mix as laser active ionic Nd the time owing between them a little less than each other the effect very, can mix higher neodymium ion concentration, and have only very low fluorescence concentration quenching effect.
Fig. 2 is the low temperature phase Nd with Cc spacer structure
3+: LaSc
3(BO
3)
4Crystalline structure figure.It is by a cover LaO
6Distorted octahedra, three cover ScO
6Distorted octahedra and quadruplet BO
3Plane triangle is formed.Each Sc ion and six oxonium ions form ScO
6Distorted octahedra.Each La ion and six oxonium ions form LaO
6Distorted octahedra.Work as Nd
3+Mix LaSc
3(BO
3)
4During crystal, it occupies the La ion position.Each LaO
6Distorted octahedra does not have the common oxonium ion, couples together LaO by La (Nd)-O-Sc (O)-O-La (Nd) chain
6Isolated each other between the distorted octahedra.Shortest distance is 6.074 between La (Nd)-La (Nd).In having the crystal of this structure and since mixed as a little less than each other the effect very between the laser active ionic Nd, so can mix higher neodymium ion concentration, and have only very low fluorescence concentration quenching effect.
Fig. 3 is low temperature phase Nd under the room temperature
3+: LaSc
3(BO
3)
4The crystal abosrption spectrogram.Abscissa is represented wavelength (millimicron), and ordinate zou is represented uptake factor (wave number).810 millimicrons absorption peak can be complementary with laser diode (LD) emitted laser wavelength.Its peak width at half height is 3.3 millimicrons, is 4 times, the Nd:YVO of Nd:YAG
41.6 times.The absorption peak of broad helps the absorption of laser crystals to pump light, has improved output rating.
Fig. 4 is low temperature phase Nd under the room temperature
3+: LaSc
3(BO
3)
4The crystallofluorescence spectrogram.Abscissa is represented wavelength (millimicron), and ordinate zou is represented relative intensity.At 1063 millimicrons very strong fluorescent emission is arranged.Its fluorescent emission life-span (τ) is 112 μ s, is 2 times of NYAB crystalline.According to formula σ=3 β λ
2/ (4 π
2τ n
2Δ V), the emission transition cross section (σ) that calculates it is 46 * 10
-20Cm
2, be 1.5 times of NYAB crystalline.τ σ is long-pending to be 3 times of NYAB crystalline.Life-span, long crystal can accumulate more particle at last energy level, had increased energy storage, helped the raising of device output rating and energy.The long-pending big crystal of σ and τ σ is realized laser generation easily, can obtain bigger output under identical power input.
Embodiment 1: the low temperature phase Nd that the case of flux methods growth has the R32 phase structure
3+: LaSc
3(BO
3)
4Crystal
LaSc with 141.68 grams
3(BO
3)
4Composite fluxing agent Li with 60,72 grams
2O-B
2O
3-LiF adopts top-seeded solution growth, with 2~5 ℃/day rate of temperature fall, and 4~30 rev/mins crystal rotating speed, the concentration of fusing assistant is 30wt.%, mixes 10at.%Nd
3+, growth temperature is controlled between 1300~1050 ℃.Grow and be of a size of 26 * 19 * 18mm
3Low temperature phase Nd with R32 phase structure
3+: LaSc
3(BO
3)
4Crystal.
Embodiment 2: the low temperature phase Nd that the case of flux methods growth has the Cc phase structure
3+: LaSc
3(BO
3)
4Crystal
LaSc with 141.68 grams
3(BO
3)
4Composite fluxing agent Li with 165.98 grams
2O-B
2O
3-LiF adopts top-seeded solution growth, with 2~5 ℃/day rate of temperature fall, and 4~30 rev/mins crystal rotating speed, the concentration of fusing assistant is 53.9wt.%, mixes 10at.%Nd
3+, growth temperature is controlled between 1050~850 ℃.Grow and be of a size of 32 * 25 * 16mm
3Low temperature phase Nd with Cc phase structure
3+: LaSc
3(BO
3)
4Crystal.Embodiment 3: the low temperature phase Nd that the case of flux methods growth has the Cc phase structure
3+: LaSc
1.5Al
1.5(BO
3)
4Crystal
With 40.73 gram lanthanum trioxides, 25.86 gram Scium trioxides, 19.12 gram aluminum oxide, 61.83 gram boric acid and 163.65 gram composite fluxing agent Li
2O-B
2O
3-LiF adopts top-seeded solution growth, with 2~5 ℃/day rate of temperature fall, and 4~30 rev/mins crystal rotating speed, fusing assistant concentration is 56.3wt.%, mixes 5at.%Nd
3+, growth temperature is controlled between 1050~850 ℃.Grow and be of a size of 40 * 32 * 12mm
3Low temperature phase Nd with Cc phase structure
3+: LaSc
1.5Al
1.5(BO
3)
4Crystal.Embodiment 4: the low temperature phase Nd that the case of flux methods growth has the Cc phase structure
3+: LaSc
1.5Ga
1.5(BO
3)
4Crystal
With 40.73 gram lanthanum trioxides, 25.86 gram Scium trioxides, 35.15 gram gallium oxides, 61.83 gram boric acid and 163.65 gram composite fluxing agent Li
2O-B
2O
3-LiF adopts top-seeded solution growth, with 2~5 ℃/day rate of temperature fall, and 4~30 rev/mins crystal rotating speed, fusing assistant concentration is 56.3wt.%, mixes 5at.%Nd
3+, growth temperature is controlled between 1050~850 ℃.Grow and be of a size of 28 * 24 * 12mm
3Low temperature phase Nd with Cc phase structure
3+: LaSc
1.5Ga
1.5(BO
3)
4Crystal.