DE2308155C3 - Phosphate laser glass with the greatest possible devitrification resistance and high chemical resistance - Google Patents

Description

45

The invention relates to a laser glass according to the preamble of claim 1.

Such a laser glass is used in quantum electronics used and serves to generate and amplify induced radiation, especially in the Laser technology.

There are known laser glasses that contain phosphorus compounds, oxides of alkali metals and oxides less often Contains earth metals.

For example, such a known glass (cf. GB-PS 11 77 731) has the following composition:

Oxides of alkali metals (in particular 2 to 40% by weight of lithium oxide),

Oxides of rare earth metals (in particular 1 to 6% by weight of neodymium oxide),
30 to 90% by weight of phosphorus oxide, maximum 20% by weight of aluminum and / or tin halides.

Such glasses are found in a number of laser systems f> 5 Men application that have a high spectral energy density of coherent radiation and low sulfur energies to ensure.

60 A disadvantage of this known laser glasses is that they have low chemical resistance, especially against atmospheric moisture, and a low Entglasungsfcstigkcit or crystallization rate at higher temperatures (200 to 700 ⁰ C). The service life of active elements produced from these glasses is thereby significantly shortened, and the production of large active elements with high optical quality is made more difficult and expensive. Because of the low peeling resistance, fine-crystalline structures and other inclusions appear in the glass during its production, which reduce the optical homogeneity and consequently the resistance of the active elements to laser radiation.

One could increase the chemical resistance of the above laser glasses by increasing theirs Increase the content of aluminum oxides and salts. In doing so, however, the decay resistance would decrease as well as the softening and melting temperature of the glass and its ability to make crucible materials dissolve, increase, which finally leads to the appearance of fine crystalline structures and the increase in the content would result in glass inclusions. These influences would lead to an increase in the threshold energy, too a decrease in the efficiency of the generation of laser radiation and the durability of the active Elements compared to laser radiation, but also to a shortening of the service life of these active elements to lead.

The chemical resistance of laser glass can be increased in other ways by increasing the content of Oxides of lanthanum (and thorium) are increased and oxides of monovalent elements are removed from the glass (Compare e.g. FR-PS 13 83 761 and US-PS 32 50 721). Such glasses have the following composition (in percent by weight):

60.3 P ₂ O ₅
13.4 La ₂ O ₃

23.4 BaO
2.9Nd ₂ O ₃

However, in this state of the art there are no precise data on the physico-chemical and laser radiation generating glass properties.

Investigations carried out by the inventors on glass of such a composition, which had been produced in volumes of 500 to ¹ , led to the following characteristics:

negative absorption at the generation frequency:

0.8-10-2 cm- ¹

Life span of neodymium: 270 jis

Density: 2.6 cm- ¹

Weight loss when boiling powder in water:

0.6-0.9%

Softening temperature: 5 JO ⁰ C

Thermal expansion coefficient: 114 χ 10- ^? / "C

Such a glass requires, in a complex manner, especially for the production in large volumes, high melting temperatures of approx. 1300 to 40D ⁰ C, at which it reacts strongly with the crucible material. It also shows poor devitrification resistance. All of this leads to a deterioration in the transparency and optical homogeneity of the glasses, and also to the presence of microcrystals and impurities. Such glasses also have a number of other deficiencies already mentioned above. In spite of its sufficiently good luminescence characteristics, it is extraordinary

08

difficult (if not impossible) to get high with them Radiation generation parameters to target. The inventor This was achieved with the glasses last described only, for dimensions of 10 mm diameter and a length of IJO mm an efficiency of to achieve a total of only 0.4% with a very high divergence of the laser radiation.

Laser glasses, the phosphorus compounds, oxides of alkali metals, compounds are also known Rare earth metals and also contain compounds of aluminum, tin, niobium and boron (such Glasses are described, among others, in O. K. D eutschbein, C. C. Partret, I. N. Cverche vsky, "Rev. Phys. Apl. «, No. 2, pp. 26 to 37, 1967). The following spectral and luminescence properties occur the following neodymium activated glasses:

a) P ₂ O ₅ -HX ₂ O, with X = lithium. Sodium, calcium, rubidium,

b) P ₂ O ₅ + YO, with Y = lead or a metal from Group II of the Periodic Table of the Elements,

c) P2O5 · AI ₂ O ₃ · X ₂ O, with X = sodium, potassium, rubidium and

However, the glasses mentioned have the same deficiencies, in particular poor chemical resistance in a humid atmosphere and weakly acidic medium.

The compositions described do not allow glasses with a given temperature range of the Establish refractive index, which is very important for lasers with low divergence of coherent radiation to manufacture.

In contrast, it is the object of the invention to provide such a device while avoiding the disadvantages mentioned To create laser glass of the type mentioned above that has a high chemical resistance, as possible extensive devitrification resistance and high optical homogeneity with good spectral and luminous properties as well as having high laser radiation generation parameters.

This object is achieved according to the invention by the characterizing part of claim 1.

The teaching of claim 2 is suitable for additionally achieving a thermo-optical constant of -10χ 10 " ⁷ Z ⁰ C to + 1Ox 10- ⁷ / ° C, in order to create lasers with a small divergence of coherent radiation.

Finally, the teaching according to claim 3 is recommended.

Advantages of the laser glass according to the invention are that it has a high chemical resistance, especially with a high content of oxides of elements of higher valency - tantalum, niobium, Tungsten, titanium and zirconium, and has the greatest possible devitrification resistance, in particular with content of oxides and compounds of barium, potassium, magnesium, strontium and boron in one Amounts of 10% by weight and less. The laser glass,

Table I.

the components of which are within the above-mentioned limits also has a low optical thermal constant.

The laser glass according to the invention has a high

5 optical homogeneity, increased resistance to laser radiation and a long service life on. It is also suitable for high-volume manufacture and for various machining Procedure well suited.

The laser glass according to the invention has at the same time covalent properties of the phosphorus-oxygen bonds and relatively small molar concentrations of multiply ionized ions, which results in small values of an uneven broadening of the active ions generated spectrum, low threshold energies, high generation efficiency of laser radiation, a large Spcktral density and a small angular divergence of the coherent radiation conditional.

The invention is explained using exemplary embodiments of the laser glass.

The production of the glass according to the invention comprises the following working steps: production of a batch, melting of the batch, melting (including refining) and cooling of the produced glass. Depending on the softening temperature of glass, the melting temperature of the batch from 900 to 135 ° "C, and the cooling temperature of 300 to 600 ⁰ C is selected.

The batch is made by mixing the ingredients in one to make the desired one Glass composition required ratio can be used. As a batch raw materials can Phosphorus pentoxide, orthophosphoric acid, oxides and phosphates, carbonates and nitrates of alkali metals and rare earth metals, oxides of zirconium, titanium, niobium, tungsten, tantalum, yttrium, boron, but aluminum also use compounds of these elements, such as niobates, tungstates and zirconates. The production Optically homogeneous glass is significantly simplified by using meltable phosphates of alkali metals and rare earth metals as well as other of the metals listed (ortho-, Pyro- and metaphosphates).

Trivalent ions of neodymium, terbium, ytterbium etc. are also added to the mixture in the form of other compounds. The presence of fluorides, perchlorates, nitrates, peroxides and carbonates of divalent and trivalent elements is desirable when neutral or oxidizing melting conditions are required, e.g. B. to prevent the transition of ions of rare earth metals into the divalent state.
In the following, exact compositions (in weight ⁰ /) of the laser glass of the invention indicated); see Tables I to III, which are analytical values. From some examples it can be seen that slight shifts beyond the claimed limit values are possible.

Components

No. of compositions 1 2 3

6a

P2O5 52.4 63.0 50.2 60.9 52.8 44.7 64.7 L12O 20.0 20.4 14.5 5.2 NaaO 22.8 16.7 4.2 25.1 4.1

continuation No. of 23 3.6 08 8.0 155 2.9 '■' 0.6 6th 8.3 5.2 5 Components 1 1.8 1.0 2.0 17.1 1.6 17.2 3.0 K2O / us; mimenxe \ / with'cii H 15.8 Rb ₂ O 19.1 2 j 2.0 4th 1.0 2.4 0.6 Nb2O-. 6.2 1.2 ZrO2 1.6 0.3 2.0 0.2 Nd2Oi 2.0 3.0 Yb ₂ Oi 5.0 CeO2 2.1 2.2 1.6 MgO 3.5 2.5 3.2 CaO 7.2 0.5 BaO 2.2 3.8 8.2 1.6 BjOi SrO 2.0 2.5 0.5 TajO-. TiO2 WOi

The laser glass of composition 1 is produced as follows:

The mixture is prepared from 144.6 g of H3PO4, 45.6 g of Na ₂ O, 38.2 g of Nb ₂ O ₅ , 3.2 g of Nd ₂ O ₃ , 4.2 g of MgO ₂ and 4.0 g of Ta ₂ O . The mixture is filled into a quartz gel and melted with continuous stirring for 5 hours. The melting temperature is 100 to 1100 "C. The pouring and cooling of the glass is carried out using a technology known per se for optical glass.

The following parameters then result for the glass produced:

Refractive index: 1.580

Density: 2.87 g / cm ¹

Thermal expansion coefficient: 136 χ 10 "7 ⁰ C

Chemical resistance (weight loss when boiling glass powder in water): 0.45%

Deglassing: more than 3 h

Lifetime of the excited state of Nd ' ⁴ :

250 ns

Coefficient of negative absorption at 1.055 μm:

2.2 x IO- ³ cm- '.

An active element made of this laser glass with a length of 130 mm and a diameter of 10 mm, which was placed in a silver-plated quartz monoblock together with an excitation lamp the following laser radiation generation parameters:

Efficiency (based on the stored electrical energy with optimal permeability of the Rcsonatorspicgcl): 2.1%
Vulnerability: 8)

Width of the spectrum generated in a resonator with plane mirrors with free generation: 15 A.

For the remaining compositions of the Lascr glass in Table 1, the batch was similar manufactured.

Typical parameters of the Lascr glass with the Compositions 2 to 6a according to Table I are:

Refractive index nj 1.5-1.6 mean dispersion (/ »/ - n _t ) χ ΙΟ ⁵ 900-1300 Density (/ [g / cm ³ ] 2.5-2.9 Type of optical homogeneity 2 Thermal expansion coefficient λ [χ 107 "C] 130-190 Softening temperature [ Tg. "C] at a viscosity of ΙΟ ¹⁵ Ρ 300-500 Chemical resistance (Weight loss) [%] 0.5-3 Devitrification [h] 3-5 Lumincline width of neodymium at one wavelength of 1.055 μm [A] 190-250 Lifetime of the excited state of neodymium 200-300 of ytterbium 1000-1500 Coefficient of negative losses a wavelength of 1.055 μm [cm-'] 2-5 ■ ΙΟ- ³ Schwencncncrgie (in impermeable Spicgcln) [J] 5-20 Generation efficiency [%] (with electrical excitation of 800 J for the active element) 1.5-2.5 Generation spectrum width [A] with free generation: Plane mirror 10-20 spherical mirrors 2-7

The batch of the glass of composition 2 was prepared from 63.0 g of P ₂ O ₅ , 20.0 g of Li ₂ O, 5.0 g of Ta ₂ O, 6.2 g of BaO, 2.2 g of TiO ₂ and 3 , 6 g Nd ₂ O ₃ . The manufacturing process for this and other glasses was the same as for embodiment 1.

The batch of glass of the composition 3 ft.s was made from 56 g P ₂ O ₅ , 40 g K ₂ O, 278.5 g NaPO ₁ , 85.5 g Nb ₂ O ,, H) g Nd ₂ O ₁ , 17, 5 g B ₂ O ₃ and 12.5 g WOi.

The threshold energy, generation efficiency, and generation spectral width are given here and below for Nd ₂ O] but not Yb ₂ Oj and Tb ₂ O _{3 containing laser glasses.}

In the further table II are glass compositions indicated the compounds of magnesium, calcium, strontium, barium, but also yttrium and boron contain. In such laser glasses in which the above-mentioned compounds and the compounds

of high quality elements present at the same time the greatest advantage is achieved, namely in the form of the greatest possible devitrification resistance with high chemical resistance of the glass. If in the laser glass a sufficiently large amount of Oxides and compounds of barium, calcium,

Table Il

Magnesium. Strontium, yttrium and boron (10-4% by weight) is present, it is possible to determine the content a Oxides and compounds of the polyvalent element without any substantial reduction in chemical strength digkeil of the glass belittle what the manufacture! reduced costs for such glasses.

Components

No. of compositions 7 8

11th

12th

PO-, 54.1 53.5 40.1 51.5 49.2 55.0 LI2O 0.1 4.1 NajO 15.0 27.7 15.8 16.9 K2O 1.0 5.0 8.2 7.5 6.9 10.0 RbO 2.1 3.1 Nb-O-, 3.2 3.0 15.0 15.3 ZrO ₂ 3.0 1.3 Nd-Oi M. 1.5 2.2 2.1 2.6 Yb-Os 3.8 4.0 CeOi 1.2 Tb2Oj 4.2 MgO 2.6 6.0 4.2 0.4 CaO 9.7 5.4 8.2 6.1 CaF. ' 2.9 SrO 4.3 8.8 2.5 BaO 25.0 3.0 B-Oi 1.1 Y-Oi 1.5 TaiO ". 1.5 TiO- ' 2.2 4.2 3.3 WOi 2.0 2.0 0.5 2.3

Typical characteristics of the compositions listed in Examples 7 to 12 of Table 2 of the laser glass according to the invention are:

Thermal expansion coefficient nc

F. demarcationfh]

Lifetime of the excited state

fn]

Schwbllcnencrgicfl]
Generation efficiency [%]
Optical heat constant [/ "C]

The other characteristic values are in the ranges. di < were given above for the exemplary embodiments 1 to 6 of the table.

In Table Nl compositions are given before laser glass, which are characterized by a low distinguish optical heat constant. Laser glass with 100-160 compositions according to the embodiments

> 5 45 games 13-20 in the IH table have a low

optical heat constant c. The principle lies in Bcrcicr 150-250 from -10 to +10 10- ⁷ / ° C. The rest

10-30 parameters of these compositions are similar to that

1.3-1.8 parameters for the above combinations

0- + 30 ΙΟ- ⁷ gen.

Table III
Components

I'.O ·.

Li.O
OK
KjO

NbO-.
ZrO;

Nd.01
CcO:
TIv 2 () 1
YhOi

No. der Ziisiimmcnsci / iimicn M '. ", 15

63.2

11.7
6.5

Lh
O. ^r >

49.0
6.0

Li

h.7

55.1

12.4 4.4

J.0 64.1
11.0

55.5

7.2
11.4

1.2

1.0

48.4

1.5

14.4

4.7

K.3

1.0

0.7

48.5

2.0 21.1

0.2 4.1

68.4

4. «(1.2

1.0

9 No. ilcr Together , sei / ungci I, Ib 17th IH 1 (11 7.8 20th continuation I i 14th I) 6.8 2.2 1.8 3.2 Components 3.4 2.0 2.1 7.1 4.1 6.0 2.0 1.0 7.1 2.2 0.4 MgO 3.0 7.7 CaO 3.2 26.5 5.7 3.4 3.0 8.3 SrO 2.5 4.3 5.5 9.5 4.3 2.0 BaO 0.4 4.0 1.0 3.3 3.0 BjOi 2.2 0.3 2.5 AL-Oi 0.5 1.0 1.1 2.1 TajO-. 1.6 0.7 TiOj WOi

Claims (3)

Patent claims: 1. Laser glass containing phosphorus compounds, oxides of alkali metals, oxides of rare earth metals and possibly contains compounds of niobium and / or zirconium, characterized in that it to achieve high optical homogeneity, chemical resistance and as far as possible Entglasungsfestigkejl with a content of the base glass in percent by weight 40 to 65 P ₂ O ₅ 5 to 30 alkali metal oxides !! 0.5 to 15 side ends of earth metal oxides 0 to 20 Nb ₂ O ₅ and / or ZrO _{2 is} additionally 2 to 45 percent by weight of at least one of the oxides of Mg, Ca, Sr, Ba, Y, B with the Maximum amounts by weight 30 MgO
30CaO
15SrO
40 BaO
10Y ₂ O ₃
20 B ₂ O ₃ as well as
2 to 30Ta ₂ O ₅ and / or TiO ₂ and / or WO ₃ ^i5> contains. 2. Laser glass according to claim I, characterized in that it is used to achieve a thermo-optical constant of -10xl0- ⁷ / "C to -I-10 χ 10- ⁷ / ° C in percent by weight 0-10 N b ₂ O ₅ and / or ZrO ₂ 5-30 at least one of the oxides of Mg, Ca, Sr ₁ Ba 2-15B ₂ O ₃ 2-20 TiO ₂ and / or Ta ₂ O ₅ and / or WO ₃ contains. 3. Laser glass according to claim 1 or 2, characterized by an addition of Al ₂ O ₃ , the total amount of B ₂ Oj and / or Al ₂ O _{3 being} 2-15 percent by weight. .15