Spectroscopic Properties of Nd3+-Doped High Silica Glass Prepared by Sintering Porous Glass

Spectroscopic Properties of Nd3+-Doped High Silica Glass Prepared by Sintering Porous Glass

Available online at www.sciencedirect.com JOURNAL OF RARE EARTHS 24 (2006) 765 - 770 www ,elsevier,codlocateijre Spectroscopic Properties of Nd3+ -...

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JOURNAL OF RARE EARTHS 24 (2006) 765 - 770

www ,elsevier,codlocateijre

Spectroscopic Properties of Nd3+ -Doped High Silica Glass Prepared by Sintering Porous Glass Qiao Yanbo (63&2k)1q2, Da Ning ( & '?)"2, Peng Mingying ([email protected])13z,Yang Liiyun ($31&5?)'~~, Chen Danping (t%ff4)'*, Qiu Jianrong (sF&*)1*3, Zhu Congshan (&&&)', Tomoko Akai (Tfj;3ff?f'+)4 ( 1 . Photo Craft Project, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai

201800, China ; 2 . Graduate School of Chinese Academy of Sciences , Beijing 100080, China ; 3 . College of Materials Science and Chemical Engineering , Zhejiang University, Hangzhou 310027, China ; 4 . National Institute of Advanced Industrial Science and Technology , Osaka 563-8577, Japan ) Received 30 June 2006; revised 10 September 2006

Abstract: A new kind of Nd3'-doped high silica glass ( SiOz > 96 Ti (mass fraction) ) was obtained by sintering porous glass impregnated with Nd3 ions. The absorption and luminescence properties of high silica glass doped with different Nd3 concentrations were studied. The intensity parameters 0 ,( t = 2 , 4 , 6) , spontaneous emission probability, fluorescence lifetime, radiative quantum efficiency, fluorescence branching ratio, and stimulated emission cross section were calculated using the Judd-Ofelt theory. The optimal Nd3' concentration in high silica glass was 0.27 % (mole fraction) because of its high quantum efficiency and emission intensity. By comparing the spectroscopic parameters with other Nd3 doped oxide glasses and commercial silicate glasses, the Nd3 -doped high silica glasses are likely to be a promising material used for high power and high repetition rate lasers. +

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Key words : high silica glass ; Nd3 spectroscopic properties ; Judd-Ofelt theory ; quantum efficiency ; rare earths Document code : A Article ID: 1002 - 0721(2006)06 - 0765 - 06 CLC number: 0314.33 ; 0482.31 +

Since the first report of laser emission from Nd3+ doped silicate glass by Snitzer"' in 1961, much attention has been paid to the research of rare earth ionsdoped laser glasses. Silica glass is a n attractive host matrix for rare earth ions because of its fine optical and mechanical properties, such as good chemicam stability, high UV transparency, low thermal expansion coefficient leading to strong thermal resistance, low nonlinear refractive index, high surface damage threshold of laser, large tensile fracture strength, and good durability. Nd3' -doped silica laser glass has been studied for over 40 years, but concentration

quenching limits its application as the host matrix. In the silica glass melt using the conventional method, Nd3+ clustering becomes prominent when neodymium concentration exceeds 0. 5 % ( mass fraction ) . To avoid clustering of rare earth ions and concentration quenching in silica glass, various methods have been used, including plasma-torch chemical vapor deposition ( CVD)[3:, sol-gel methodL4', and modified sol-gel method using zeolite XI5]. Here, a new method to fabricate Nd3'-doped silica glass has been introduced on the basis of the technique of porous silica g l a ~ s - ~ - ~ ' . Since the content of SiO, is close to 96% (mass frat-

'*

* Corresponding author (E-mail : ybqiao @ siom .ac . cn )

Foundation item: Project supported by the National Natural Science Foundation of China (50125258 and 60377040), the Shanghai Nano-Tech Promote Center (0352nm042) Biography: Qiao Yanbo (1980- ) , Male, Doctor; Research field: Rare earth-doped glasses and photonic crystal fibers Copyright 0 2 0 0 6 , by Editorial Committee of Journal of the Chinese Rare Earths Society. Published by Elsevier B . V . ,411 rights reserved.

JOURNAL OF RARE EARTHS, Vol. 2 4 , N o . 6 , Dec . 2006

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tion), this glass is referred to as "high silica glass". In this study, the absorption, fluorescence spectra, and fluorescence lifetime of high silica glass were measured. The optimal Nd3'-doped concentration in the high silica glass was confirmed according to its radiative quantum efficiency and emission intensity. On the basis of Judd-Ofelt theory l o 3 ' l 1 , the spectroscopic properties of high silica glass with different Nd7+ concentrations have been studied. The intensity R,( t = 2 , 4, 6 ) was calculated from the absorption spectra for access to theoretical spectroscopic quantities, such as spontaneous emission probability, fluorescence lifetime of the 4F312level, radiative quantum efficiency for the 4F312 +4111,2 transition, and fluorescent branching ratio. The stimulated emission cross section of the at 1060 nm was estimated from transition 4F312+4111i2 the fluorescent spectra. As the Nd3' concentration in the glass increases, concentration quenching is found to be restrained efficiently. By comparing the spectroscopic parameters with other Nd3' -doped oxide glasses and commercial silicate glasses, this material is suggested to be a candidate for an attractive gain medium for solid state lasers with high power and high repetition rate.

1 Experimental Porous silica glass was obtained by removing borate phase from phase-separated alkali-borosilicate glass in hot acid solutions. This method is similar to the treatment process used in manufacturing Vycor glass . The analytical composition of the porous glass obtained by phase separating and acid treating 1(Na20+ CaO) was 9 7 . 0 SiO2*2.1 B 2 03*0. 8A 1203*0. ( % , mass fraction). The obtained porous glass is a transparent material whose pore sizes are less than 4 nm and the pores nominally occupy about 40% of the volume of the glass. Then the porous glasses were immersed into 0. 05, 0. 10, 0. 15, 0. 20, 0. 25, 0.30, 0.35 rno1-L-l solution of Nd(N03)3 for 1 h and dried at room temperature. After that, the porous glasses impregnated with Nd3+ ions were sintered at 1100 'T for 2 h . The final products were compact and transparent. The seven samples were denoted as A , B , C , D , E , F , G , respectively with increasing Nd3+ concentration. In order to analyze their spectroscopic properties, the glass samples were cut and polished. The density of the sample was measured using the buoyancy method on the basis of the Archimedes pnnciple with distilled water as the immersion liquid. The refractive index was measured with the Abbe refractometer . Here slight change of density and refraction of the samples were ignored. The density is 1.98 g.cm-3 and

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the refractive index is 1.462. The absorption spectra were recorded with a Jasco V-570 UV/VIS/NIR spectrophotometer. The infrared luminescent spectra were obtained with ZOLIX SBP300 spectrophotometer under 808 nm LD excitation. The fluorescence lifetime was recorded with a modulated 808 nm LD with maximum power of 2 W and the signal detected by InGaAs photodetector in TRIAX550 was recorded using storage digital oscilloscope (Tektronix TDS3052). Errors in the absorption, fluorescence, and lifetime measurements are estimated to be 5%, l o % , and +- 10% , respectively. All the measurements were made at room temperature.

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2 Results and Discussion 2.1

Absorption spectrum and Judd-Oflet analysis

The absorption spectra of the glasses with various Nd3' concentrations are shown in Fig. 1 . The absorption peaks are attributed to the transitions of Nd3* from the ground state 41g12 to the excited states as shown in Fig. 1 . For Nd3' , the electric-dipole transitions are predominant. The line strengths of the electric-dipole J = 9/2) manifold to transitions from the ground 41912( the excited J'-manifold can be obtained by the following re~ation.'~]

(1) where, N o is the Nd3+ concentration and expressed in ion*cm-3, n is the refractive index of the sample, A p is the peak wavelength of the absorption band, and K is the absorption coefficient at wavelength A and defined as

"1

=ln10 !" OD(A)dh L

~(h)dA

4

5

6

7

8

9

1 0 1 1 1 2

Wavelength/lOZnm Fig. 1

Room temperature absorption spectra of high silica glasses (absorption spectra were normalized with the thickness of glass samples)

Qiao Y B et a l . Spectroscopic Properties of Nd3' -Doped High Silica Glass

767

Table 1 Line strengths of electric-dipole transitions, doping concentrations, densities, and refractive indices of Nd3' -doped high silica glasses' B

A

D

C

E

F

G

J'-manifold Smea

S ~ I

Smea

Sca~

Smea

S ~ I

0.805 4F312 2.282 4Fsi2 + 2 H 9 i 2 2.501 2.398 2.440 2.212 4F7i2 + 4S3i2 1.958 2.115 2.129 0.675 0.162 0.521 0.161 4F9n 4G5iz + 2 G i 2 10.375 10.406 8.494 8.513 7.809 7.824 2.077 1.644 1.724 1.462 1.55 1.335 2K13/2+4G/2+4Gg/2 Rms AS/(10-20ern2) 0.466 0.305 0.238 Rms error/% 5.12 4.02 3.39 0.18 0.27 Content/%(mol fraction) 0.09 n 1.462 1.462 1.462 0.521

*

411 values of S,,

1.008 0.607

0.901 2.377 2.227 0.164

0.579 2.330 2.137 0.430

x n,

I =2.4,6

u(,)

S'J']J'> I* (2) where, the elements U " ) ( t = 2 , 4 , 6 ) are the doubly reduced unit tensor operators calculated in the intermediate coupling approximation, which is almost independent of the change of host."'. Intensity parameters a,( t = 2 , 4 , 6 ) are phenomenologically independent of electronic quantum numbers with the ground 4f3 configuration of Nd3+ ion. By least-root-means-square (rms) fitting between Eqs. (1) and ( 2 ) , the three incan be obtained and the Valtensity parameters nn2,',6 ues are shown in Table 2. Because of the inhomogeneous broadening, certain excited levels of IUd3' are generally not resolved. In this study, six absorption bands that correspond to the transitions from the ground state 'Igi2 level to the excited levels 4F3/2,4F5iz+ 2H9/2,

+ " 3 / 2 > 4F9/23 4G5/2 + 'G712 7 'K13,2 + 'G7/2 + 'G9D are used for the fitting. Among the three intensity parameis most sensitive to the local structure and ters, glass composition, which reflects the amount of covalent bonding and asymmetry of local environment near Nd3+ site. As shown in Table 2, On2of Nd3+-doped high silica glass is relatively large. Large value of f12 suggests less centrosymmetric coordination environment around Nd3+ in high silica This indicates that the structure of high silica glass is very different from the conventional glasses. From the intensity parameters, the line strengths of electric-dipole

n2

Smea

Sca~

Smea

Scs~

0.115 0.145 6.773 6.789 1.019 1.286 0.273 4.43 0.36 1.462

4.971 4.977 1.101 1.019 0.085 1.82 0.45 1.462

Smra

Scai

0.563 0.680 0.569 1.905 1.858 2.257 1.748 1.791 1.898 0.134 0.130 0.179

Scai

0.754 0.607 0.712 2.080 2.154 2.061 2.025 1.979 2.049 0.145 0.203 0.146

4.754 4.757 1.091 1.083 0.154 3.30 0.54 1.462

4.605 4.607 1.059 1.047 0.093 2.03 0.63 1.462

and S,,, are in unit of 1 x lo-*' em2

where, OD ( A ) is the measured optical density as a function of wavelength A and L is the thickness of glasses. The values of S,,, extracted from the absorption spectra are shown in Table 1 . Values of Nd3+ concentrations and refractive indices of all the glass samples are also shown in Table 1. According to J-0 theory, the line strength can also be expressed as : I <4f"[aSLlJ I1 I1 4f"[a' Scal(.I- J ' ) =

'F7i2

Smea

0.609 0.864 2.198 2.137 1.882 1.951

transitions Seal were then calculated using Eq . ( 2 ) and are shown in Table 1 . The Rms deviation between the experimental and calculated line strengths is defined as :

/ i ( s m e -8 ScaJ2

RmsAS =

) i l l

(3) ili - 3 where, >Vis the number of absorption bands taken into account in the above calculations. The relative error is defined as: RmsA S Rms error = x 100% Rms S where,

2'

~

The values of Rms AS and Rms error are shown in Table 1 .

2. 2 Luminescence properties Spontaneous emission probabilities A;;, , corresponding to transitions from the 4F3,2manifold ( J = 3/2), which are generally used as the upper level for Nd3+ -doped solid-state laser, to the lower J ' -manifolds 'IlJ can be calculated by means of the following relation[l3]:

A$( J

-

Table 2

64x4e

1')= 3 h ( 2 J

+ l)Aa

n(n2+2Yx

9

I

c n,

=2,4.6

Judd-oflet parameters of Nd3+-doped high silica glasses

Parameters

.4

B

C

D

E

F

G

0 2

5.02 3.81 2.56

5.07 3.35 2.94

5.26 3.40 3.68

5.27 3.54 3.74

5.38 3.47 3.85

5.64 3.52 4.38

5.70 3.45 4.52

0 4 0 6

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The fluorescence lifetime and radiative quantum efficiency at critical concentration (sample C ) are 315 11s and 5 1% , respectively. It is known that when a small amount of Nd3' ions is doped into glasses, certain changes occur in the network structure"': . Therefore, a change in the environment around Nd3* ions may be the main reason for the changes of fluorescence lifetime and radiative quantum efficiency at low Nd3' ion concentrations. But at higher Nd3' concentration ( 2 0. 27 % ( mole fraction ) ) , concentration quenching process becomes predominant and fluorescence lifetime and radiative quantum efficiency decrease from 3 15 to 240 ,us and from 5 1% to 41 % , respectively. The fluorescence spectra of the glasses were recorded in a spectral range from 850 to 1450 nm. As an example, the spectrum of sample C is shown in Fig. 3 . The three fluorescence peaks correspond to the transitions of 4F312-+41gi2 ( 900 nm) , 4F3/~+4111/2 ( 1060 nm) , 4F312+4113/2(1330 nm) , respectively. with large stimulated The transition of 4F312+411112 emission cross section has been widely used as the laser channel in Nd3'-doped solid state lasers, so this research mainly focuses on the transition at the corresponding 1060 nm band. The fluorescence spectra of the transition 4F312+4111i2 for the glass samples with dif-

where, A , is the peak wavelength of the emission bands and values of I j ( t )( t = 2 , 4 , 6 ) have been proposed by Kaminskii et alLL6'.The branching ratio ,8 is a critical parameter to the laser designer, because it characterizes the possibility of attaining stimulated emission from any specific transition. It is given as :

A, ; ;

f=w

(7)

I'

The fluorescence lifetime of the 4F3i2manifold is :

r r=

~

1 A$

c J'

And the radiative quantum efficiency is defined as :

where, r f is the fluorescence lifetime of the 4F312 manifold and can be obtained from the fluorescence decay curve. Table 3 shows these obtained values of Nd3'doped glasses. Fig. 2 shows the variations of fluorescence lifetime and radiative quantum efficiency with increasing Nd3+ concentration. When Nd3 ion doped exceeds the critical concentration of 0.27 % (mole fraction) , fluorescence lifetime and radiative quantum efficiency decrease sharply because of concentration quenching.

Table 3 Spectroscopic properties of Nd3 -doped high silica glasses +

4F3n+41~3/z

4F3n+41ii,z

4Fw+41w

4F3,2lifetime

Glasses

A

B C D E F G

0.0

Als-'

PIS

Als-'

PI%

Als-'

PI%

rJps

rdps

71%

109.42 137.44 173.23 160.51 172.36 185.53 190.45

9 10 11 10 10 11 11

585.42 685.95 810.56 798.73 803.18 859.52 887.70

49 49 50 48 48 50 51

490.64 570.33 631.34 683.48 685.27 675.37 671.89

42 41 39 42 42 39 38

845.68 720.12 619.65 614.47 601.36 579.84 568.61

330 325 315 310 290 250 240

39 45 51 50 48 43 41

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Nd'* ion concentratton/(%,mole fraction)

Fig . 2

Fluorescence lifetime and radiative quantum efficiency transition as function of Nd3' concentraof 4F312+4111,2 tions

Wavelcngth/lO2 nm Fig. 3

Room temperature fluorescence spectrum of Nd3* -doped high silica glass ( Nd3 concentration : 0. 27 % ( mole fraction) ) +

Qiao Y B et a1 . Spectroscopic Properties of Nd3' -Doped High Silica Glass

ferent Nd3+ concentrations are shown in Fig. 4. As Nd3+ ion concentration increases, the fluorescence intensity changes regularly . The fluorescence intensity reaches a maximum when Nd3 -doped concentration is close to 0 . 27% (mole fraction). Then the fluorescence intensity decreases distinctly because of concentration quenching. From Figs.2 and 4, the concentration quenching process becomes predominant when the Nd3' ion concentration exceeds 0. 27% ( mole fraction). The optimal Nd3+-doped concentration in high silica glass is nearly 0.27% (mole fraction) because of its high fluorescence intensity and radiative quantum efficiency. The higher Nd3' -doped concentration indicates that porous glass can disperse Nd3' ions uniformly in the glass and restrain concentration quenching effciently . First, after repeated hot acid solution leaching and washing, porous glass has large specific surface area and high surface activity. When immersing porous glass in Nd ( N 0 3 ) 3 solution, Nd3t ions will cling to the pore surface firmly to reduce surface activity. By this way, Nd3' ions are uniformly dispersed on the surface of porous glass. Second, the sintering temperature of high silica glass is only 1100 "c , low temperature is not enough to melt the silica porous glass. Since the volume of the porous glass shrinks under solid state, so to speak, liquid flow does not occur, and Nd3' ions move difficultly. So, the Nd3' ions are dispersed in the porous glass and the solubility of Nd3' in high silica glass is improved effectively. The Nd3 fluorescence bands are asymmetric ; therefore, an effective linewidth Ah eff is defined by-'*! :

769

+

Wavelengthhm

Fig.4

Fluorescence spectra of transition 4F3,244111,2for high silica glass with different Nd3+ concentrations (Concentration ( % , mole fraction) : A 0. 09 Nd3' ; B 0. 18 Nd3' ; C 0 . 2 7 Nd3' ; D 0 . 3 6 Nd3' ; E 0 . 4 5 Nd3* ; F 0.54 Nd3' ; G 0.63 Nd3')

Table 4 Values of A,, ALeP1,and u , . of~ Nd3+-dopedhigh silica glasses Glasses

AJnm

AA,ff/nm

61 mi10-20 cm2

A B C D E F G

1059 1059 1059 1059 1058 1059 1060

40.73 41.20 41.82 39.63 39.42 39.26 38.76

2.14 2.23 2.38 2.29 2.34 2.41 2.48

Table 5

+

(9) where, I ( A ) is the emission intensity at wavelength A and the I,,, is the emission intensity at peak emission wavelength. The stimulated emission cross section of the transition 4F3,2+411112 at 1060 nm can be estimated from the fluorescence spectra by"': :

(10) Table 4 shows the values of A e , AA e f f , and 0 ,06 of Nd3' -doped high silica glasses. In Table 5'19-24', the main spectroscopic parameters of various Nd3' -doped oxide glasses and commercial silicate laser glasses are shown. The table reveals that the spectroscopic parameters of Nd3 -doped high silica glasses are better than most of the listed Nd3+doped oxide glasses. Compared to these listed commercial silicate glasses, the high silica glasses obtained by porous glasses method are more preponderantly used as +

Comparison of spectroscopic parameters of certain Nd3'-doped oxide glasses and commercial silicate glasses

Host

r y / p 71% al,M/lO-ZO cm2 Refs.

7%[email protected] 55P205-40Ba0-5A1203 60b03-35Ba0-5TiO~ [email protected] 40Bi203-60b03 hO-BaO-Na20 Na20-Al20,- B2O3 [email protected] Commercial glasses 3699A ED-2 LSG91H Sample C

360 350 110 310 95 90

59 300 520

310 Mo 315

97 87 30 95 54 22 20 52 83 78 51

2.28 3.66 2.64 2.60 3.9 2.4 3.1 0.19 1.05 2.71 2.45 2.38

19 19 19 19 20 21

22 23 24 24 24 This work

Nd3 -doped laser materials. The results indicate that this material is a candidate for an active medium for solid state lasers used of high power and high repetition rate lasers. +

3 Conclusion To avoid clustering of rare earth ions and concentration quenching in the silica glasses, a new method

770

on the basis of porous glass was used to obtain Nd3' doped high silica glasses. The porous glass can disperse Nd3' ions uniformly in the glass and restrain concentration quenching efficiently . The abundant pores of the porous glass can disperse the Nd3+ ions before sintering . In the process of sintering , low temperature (1100 "c ) is not enough to melt the silica glass and the clustering of Nd3' ions becomes difficult. At the optimal Nd3' concentration of 0. 27% ( mole fraction), the radiative quantum efficiency and the stimulated emission cross section are 51 % and 2 . 3 8 x lo-*' cm2, respectively. By comparing the spectroscopic parameters with other Nd3t -doped oxide glasses and commercial silicate glasses, the Nd3+ -doped high silica glasses obtained by the method on the basis of porous glass are likely to be a new material used for high power and high repetition rate lasers.

References : [ 1] Snitzer E . Optical master action of Nd3' in a barium crown glasses [ J ] . Phys. Rev. Lett. , 1961, 7 ( 1 2 ) : 444. [ 21 Gallant E I , Kondrat'ev Y N , Przhevuskii A K , et a1 . Stimulated emission of neodymium ions in quartz glass [ J ] . JETP Lett. , 1973, 18: 372. [ 31 ilrai K , Namikawa H , Kumata K , et a1 . Aluminum or phosphorus co-doping effects on the fluorescence and structural properties of neodymium-doped silica glass :JI. J . Appl. Phys., 1986, 59: 3430. [ 4 ] Thomas I E , Payne S A , Wilke G D . Optical properties and laser demonstrations of Nd-doped sol-gel silica glasses [ J 1 . J . Non-Cryst . Solids, 1992, 151 ( 3 0 ) : 183. [ 5 ] Fujimoto Y , Nakastuka M . A novel method for uniform dispersion of the rare earth ions in SiOz glass using Zeolite X [ J ] . Non-Cryst. Solids, 1997, 215: 182. [6! Xia J , Chen D , Qiu J , et al. Rare-earth-doped silica microchip laser fabricated by sintering nanoporous glasses [ J ] . Opt. Lett., 2005, 3 0 ( 1 ) : 47. [71 Chen D , Miyoshi H , Akai T , et a1 . Colorless transparent fluorescence material : Sintered porous glass containing rare earth and transition metal ions [ J ] . Appl . Phys , Lett., 2005, 86: 31908. [ 81 Liu W , Chen D , Miyoshi H,et al. Colorless transparent fluorescence material at the VLV excitation: The leached sintered glass with impregnation of Th3' ions [ J ] . Chem. Lett., 2005, 34: 1176.

JOURNAL OF RARE EARTHS, Vol. 2 4 , N o . 6, Dec

. 2006

[ 9 ] Da N , Yang L , Peng M , et al. Preparation and spectroscopic properties of Er3+ -doped high silica glass fahricated by sintering nanoporous glass [ J ] . Mater. Lett. , 2006, 60: 1987. [ 101 Judd R . Optical absorption intensities of rare-earth ions [ J ] . Phys. R e v . , 1962, 1 7 2 ( 3 ) : 750. [ l l ] Oflet G S. Intensity of crystal spectra of rare-earth ions [ J ] . J . Chem. Phys., 1962, 3 7 ( 3 ) : 511. [ 121 Vogel. Glass Chemistrq. [ M I . Springer-Verlag, 1994. 92. [ 131 Krupke W F . Optical absorption and fluorescence intensities in several rare-earth-doped Y203 and LaF3 single crystals [ J ] . Phys. Rev., 1966, 1 4 5 ( 1 ) : 325. [ 141 Carnal1 W T , Fields P R , Rajnak K . Electronic energy levels in the trivalent lanthanide aquo ions. I . Pr3' , Nd3', Sm3', Dy3', H o 3 + , E r 3 + , and Tm3' [ J ] . J . Chem. Phys., 1968, 4 9 ( 1 0 ) : 4424. [ 15 Weher M J , Myers J D , Blackburn D H . Optical properties of Nd3' in tellurite and phosphotellutite glasses [ J ] . J . Appl. Phys., 1981, 52: 2944. [ 161 Kaminskii A A , Boulon G , Buocristiani M , et al. Spectroscopy of a new garnet Lu3Sc2Ga3OI2 : Nd" [ J ] , Phys. Stat. Sol. ( a ) , 1994,141(2): 471. [17] Sampaio A , Baesso M L , Gama S, et al. Rare earth doping effect on the elastic moduli of low silica calcium aluminosilicate glasses [ J ] . J . Non-Crystal Solids, , 2002, 3 0 4 ( 1 - 3 ) : 293. [ 181 Reisfeld R , Greenberg E , Brown R N , et a1 . Fluorescence of europium ( Ill ) in a fluride glass containing zirconium [ J ] . Chem. Phys. Lett., 1983, 95: 91. [ 191 Jiang Z , Yang J , Dai S . Optical spectroscopy and gain properties of Nd3' -doped oxide glasses [ J . J . Opt, SOC.Am. B , 2004, 2 1 ( 4 ) : 739. [ 2 0 ] Chen Y, Huang Y , Huang M , et a1 . Effect of Nd3+ on the spectroscopic properties of bismuth borate glasses [ J ] . J . Am. Cwram. S o c . , 2005, 8 8 ( 1 ) : 19. [21] Gan F , Chen S , Hu H . Nonradiative energ- transfer process in Nd3' doped laser glasses 151. Sci. China (in C h i n . ) , 1981, 3: 289. [22: Mehta V , Aka G , Dawar A L , et al. Optical Properties and spectroscopic parameters of Nd3+ doped phosphate and borate glasses [ J ] . Opt. Mater. , 1999, 12( 1 ) : 53. [23I Hou Z , Su C , Zhang Y , et al. Effect of crystallization of Li20-A1203-Si02glasses on luminescence properties of Nd3' ions [ J ] . Journal of Rare Earths, 2006, 2 4 ( 4 ) : 418. Induced-emission cross sections in [24I Krupke W F. neodymium laser glasses 1J 1 . IEEE J . Quant . Electron., 1974, Q E - lO(4): 450.