JP2002211950A - Light amplifying glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light amplifying glass capable of amplifying light of S+ band and S band, less liable to thermal damage due to excited light and less liable to breaking even when drawn into a fiber. SOLUTION: The light amplifying glass is obtained by adding 0.001-10 mass% Tm to a matrix glass containing 21-80 mol% Bi2O3 and also containing GeO2. Preferably the matrix glass further contains Ga2O3 or CeO2 and satisfies Bi2O3+ GeO2+Ga2O3+CeO2>=70 mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light amplification glass. In particular, the present invention relates to an optical amplifier glass capable of amplifying light having a wavelength of 1.4 to 1.5 μm in a wide band.

[0002]

2. Description of the Related Art For the purpose of application to an optical amplifier in an optical communication system, development of an optical amplification glass comprising a core glass and a cladding glass and to which a rare earth element is added as a glass for the core glass has been advanced. On the other hand, in order to cope with the diversification of communication services expected in the future, a wavelength division multiplexing optical communication system (WDM) for increasing the transmission capacity has been proposed. In WDM, as the number of wavelength multiplexing channels increases, the transmission capacity increases.

Conventionally, the C band (wavelength: 1530 to 156)
0 nm) or L band (wavelength: 1570-1600 n)
m) Er (erbium) as a glass suitable for optical amplification
Is added to the S ⁺ band (wavelength: 14).
50 to 1490 nm) and the S band (wavelength: 1490)
Tm as a glass suitable for optical amplification of
Light amplification glasses to which (thulium) is added have been proposed.

[0004] Pump light is incident on the Tm-doped optical amplification glass together with the light to be amplified, that is, the signal light, and the signal light is amplified using the stimulated emission transition of Tm. When performing excitation by the up-conversion method,
Typically, it is 1.0 to 1.6 μm. The Tm-doped optical amplification glass is usually used as a fiber.

[0005]

In the Tm-doped optical amplification glass, optical amplification of the S ⁺ band and the S band is performed by using the stimulated emission transition between ³ H ₄ ⁻³ F ₄ . However, below the ³ H ₄ level there is a level ³ H ₅ that is approximately 4300 cm ⁻¹ apart and close. Due to this close level ³ H ₅ , multiphonon relaxation in the stimulated emission transition is increased and radiation relaxation is reduced, and as a result, luminous efficiency, and thus light amplification factor, may be reduced.

[0006] As a Tm-added light amplification glass, for example, a light amplification glass in which Tm is added to fluoride glass has been proposed. Fluoride glass has the advantage of less multiphonon relaxation than oxide glass. However, the glass transition point T _g of the fluoride glass is low (typically 320
℃ or less), and there was a possibility that thermal damage would occur if the intensity of the excitation light was increased. Further, the Vickers hardness H _V of fluoride glass is low (typically 2.4 GPa) easily scratched because, the scratches there is a possibility to break causing upon the fiber of.

As an optical amplification glass obtained by adding Tm to a fluoride glass, for example, a composition expressed in mol% is Zr.
F ₄ : 52.53%, BaF ₂ : 20.20%, LaF
_{3: 3.03%, AlF 3:} 4.04%, NaF: 2
The matrix glass is 0.20% Tm are added 1.19% by mass percentage, _{T g} is 200 ° C., the peak wavelength of the emission spectrum is 1452nm, Tm-doped fluoride glass the half width of 76nm ZBLAN is known (Applied Optics, 39
(27), 4979-4984 (2000)).

Further, as a light amplification glass in which Tm is added to tellurite glass, for example, the composition expressed in mol% is TeO ₂ : 75%, ZnO: 10%, Na ₂ O: 15%.
In the matrix glass having a Tm of 1.
Are added 23%, the peak wavelength of the emission spectrum is 1458Nm, but the half width is known Tm-doped tellurite glass is 114 nm, the The _{T g} lower 2
95 ° C. (Applied Optics, 39
(27), 4979-4984 (2000)).

Further, PbO: 56 mol%, Bi ₂ O ₃ :
A matrix glass composed of 27 mol% and Ga ₂ O ₃ : 17 mol% has a Tm of 0.01% by mass percentage and 0.1% by mass.
Glass doped with 05% or 1.5% (Pb with Tm added)
_{O-Bi 2 O 3 -Ga 2} O 3 glass) is disclosed (Applied Optics, 34 (21) , 42
84-4289 (1995)). The annealing temperature and Knoop hardness of the matrix glass are 319 ° C. and 2.2 G, respectively.
Pa (Phys. Chem. Glasses, 2
7, 119-123 (1986)). Annealing point may be regarded as equal to T _g, also significant changes in T _G be added Tm up to 1.5% it is considered that there is no. That is, the Tm of the Tm-added PbO—Bi ₂ O ₃ —Ga ₂ O ₃ glass
_g is still about 320 ° C., and the thermal damage may occur.

[0010] In addition, Knoop hardness case of optical glass _{H V}
The 0.4~1.3GPa lower than considering the (glass Encyclopedia, 352 pp., Asakura Shoten, 1985 issue), said Tm-doped _{PbO-Bi 2 O 3 -Ga 2} O 3
_{H V} of the glass is considered to be in the range of 2.6～3.5GPa, in which it can not be said never high. The present invention has a high _{T g} and _{H V,} and, ^{S +} band and S
It is an object of the present invention to provide a light amplification glass capable of amplifying band light.

[0011]

SUMMARY OF THE INVENTION The present invention is an optical amplification glass obtained by adding 0.001 to 10% by mass% of Tm to a matrix glass, wherein the matrix glass contains 15% Bi ₂ O ₃ . ~ 80 mol% and GeO
₂ is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The optical amplifier glass of the present invention has a _Tg of 3
Preferably it is 60 ° C. or higher. The reason is that when a laser beam having a high intensity is used as the excitation light for optical amplification, the temperature of the glass locally increases, and the _Tg becomes 360 ° C.
If it is less than 3, the glass may be thermally damaged, resulting in an increase in light loss and insufficient light amplification.
More preferably 400 ° C. or higher, particularly preferably 420 ° C.
That is all.

[0013] _{H V} of the optical amplifying glass of the present invention 3.6GP
It is preferably at least a. If it is less than 3.6 GPa, it may be easily broken when it is made into a fiber. More preferably, 3.7 GPa or more, particularly preferably 4.0 GPa.
Pa or more.

Tm is added to the matrix glass of the present invention in order to provide a light amplification function. If the amount of addition of Tm in terms of mass percentage (Tm addition amount) is less than 0.001% when the matrix glass is taken as 100%, the optical amplification rate decreases. Preferably it is 0.01% or more, more preferably 0.05% or more. If it exceeds 10%, vitrification becomes difficult, or the optical amplification rate is rather lowered due to concentration quenching. Preferably it is 1% or less, more preferably 0.5% or less.

Next, the components of the matrix glass in the present invention will be described below by simply expressing mol% as%. Bi ₂ O ₃ is an essential component. Its content is 15%
If it is less than 1, the optical amplification rate decreases or the phases are separated. It is preferably at least 15.5%, more preferably at least 20%, further preferably at least 25%, particularly preferably at least 30%, most preferably at least 35%. At over 80%
Vitrification tends to be difficult, devitrification during fiber processing, or T _g is too low. Preferably 70% or less, more preferably 60% or less, particularly preferably 55% or less,
Most preferably, it is 48% or less.

GeO ₂ is a network former and is essential. The content of GeO ₂ is preferably 5 to 80%. If it is less than 5%, vitrification becomes difficult or devitrification may occur during fiber processing. It is more preferably at least 15%, particularly preferably at least 20%, most preferably at least 25%. If it exceeds 80%, the light amplification rate may be reduced, or devitrification may occur during fiber processing. More preferably 75% or less, particularly preferably 60%
Or less, most preferably 55% or less.

Ga ₂ O ₃ is not essential, but may be contained up to 30% in order to increase the wavelength width at which gain can be obtained or to suppress devitrification during fiber processing. 3
If it exceeds 0%, crystals may precipitate during glass production, and the transmittance of the glass may be reduced. Preferably it is 25% or less. When Ga ₂ O ₃ is contained, its content is 0.5%
It is preferable that it is above. More preferably 1% or more,
It is particularly preferably at least 3%, most preferably at least 5%.

CeO ₂ is not essential, but is contained up to 10% in order to prevent Bi ₂ O ₃ in the glass composition from being reduced during melting of the glass to precipitate as metallic bismuth and lowering the transparency of the glass. May be. If it exceeds 10%, vitrification may be difficult, or yellow or orange coloring may become strong, whereby the transmittance of the glass may be reduced, and the background loss at the excitation light wavelength or signal light wavelength may increase. It is preferably at most 1%, more preferably at most 0.5%, particularly preferably at most 0.3%. C
When eO ₂ is contained, its content is preferably 0.01% or more. More preferably 0.05% or more,
It is particularly preferably at least 0.1%. In order to avoid a decrease in the transmittance of glass, the content of CeO ₂ is set to 0.1.
It is preferably less than 5%, more preferably substantially not containing CeO ₂ .

Ga₂O₃Or CeO₂Containing Bi
₂O₃, GeO₂, Ga₂O₃And CeO₂Content of
Total Bi of₂O₃+ GeO₂+ Ga₂O₃+ CeO₂But
It is preferably at least 70%. Also, Bi₂O₃To
15-48%, GeO₂15 to 60%, Ga₂O₃To
0.5-25%, CeO₂0.1 to 0.3%
Is more preferable. Bi ₂O₃15-48%, Ge
O₂25-60%, Ga₂O₃5-25%, CeO
₂Is more preferably contained at 0.1 to 0.3%.

In the present invention, the matrix glass is represented by the following oxide-based mol%, 15 to 80% of Bi ₂ O ₃ , 5 to 80% of GeO ₂ , 0 to 30% of Ga ₂ O _{3, and} 0 to 10 of CeO _{20. %, WO 3 0~10%, TeO} 2 0~20%, Al 2 O 3 0~30%, Li 2 O 0~10%, Na 2 O 0~20%, K 2 O 0~20%, ZnO 0-20%, MgO 0-20%, CaO 0-20%, SrO 0-20%, BaO 0-20%, TiO ₂ 0-10%, ZrO ₂ 0-10%, SnO ₂ 0-10%, Preferably consists essentially of

Since Bi ₂ O ₃ , GeO ₂ , Ga ₂ O ₃ and CeO ₂ have been described above, components other than these 4 components will be described below. WO ₃ is not essential, but may be contained up to 10% in order to increase the wavelength width at which gain can be obtained. If it exceeds 10%, the light amplification rate may be reduced.

TeO ₂ is not essential, but may be contained up to 20% in order to increase the optical amplification factor. If it exceeds 20%, crystals may precipitate during glass production, and the transmittance of the glass may be reduced. It is preferably at most 10%, more preferably at most 5%. When TeO ₂ is contained, its content is preferably 1% or more. More preferably 2
% Or more.

Al ₂ O ₃ is not essential, but may be contained up to 30% in order to suppress devitrification at the time of fiber processing. If it exceeds 30%, crystals may precipitate during glass production, and the transmittance of the glass may be reduced. More preferably 20%
Or less, particularly preferably 15% or less. When Al ₂ O ₃ is contained, its content is preferably at least 0.1%. More preferably 1% or more, particularly preferably 2%
% Or more.

The total content of Ga ₂ O ₃ , Al ₂ O ₃ and TeO ₂ is preferably 50% or less. 50
%, Crystals may be precipitated during glass production, and the transmittance of the glass may be reduced. It is more preferably at most 30%, particularly preferably at most 25%, most preferably at most 20%. Further, the total of the contents is preferably 2% or more,
It is more preferably at least 4%.

Although Li ₂ O, Na ₂ O and K ₂ O are not essential, they may be contained up to 10%, 20% and 20%, respectively, in order to suppress devitrification during fiber processing.
Any of ZnO, MgO, CaO, SrO, and BaO is not essential, but each may contain up to 20% to suppress devitrification during fiber processing. TiO ₂ , ZrO
₂ and SnO ₂ are not indispensable, but each may be contained up to 10% in order to suppress devitrification during fiber processing.

Although the preferred matrix glass consists essentially of the above-mentioned components, it may contain other components within a range not to impair the object of the present invention. The total content of the "other components" is preferably 10% or less.

The "other components" will be described below.
In order to facilitate glass formation or to suppress devitrification during fiber processing, Cs ₂ O, CdO, PbO,
Y ₂ O ₃ , La ₂ O _{3 and the} like may be contained. Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Yb ₂ O ₃
And the like. Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂
When O ₃ or Yb ₂ O ₃ is contained, the content of each component is preferably 0.001% or more. It is more preferably at least 0.01%, particularly preferably at least 0.1%.

[0028] Incidentally, PbO is preferably not substantially contained because it may decrease H _V. Also, S
Since there is a possibility that iO ₂ or B ₂ O ₃ may increase multiphonon relaxation, it is preferable that neither iO ₂ nor B ₂ O ₃ be substantially contained.

The method for producing the optical amplification glass of the present invention is not particularly limited. For example, the raw materials are mixed, put into a platinum crucible, a platinum-gold alloy crucible, an alumina crucible, a quartz crucible or an iridium crucible, and melted in air at 800 to 1300 ° C. The light amplifying glass of the present invention can be produced by a melting method of casting into a mold. In addition, in order to reduce the moisture in the glass and suppress the increase in multiphonon relaxation, it is preferable that the moisture in the melting atmosphere in the melting method is small,
For example, use of dry nitrogen or dry air is preferable.

Further, the light amplifying glass of the present invention may be manufactured by a method other than the melting method, for example, a sol-gel method or a vapor deposition method. The optical amplification glass fiber can be produced by producing a preform on the basis of the optical amplification glass of the present invention produced in this way and forming it into a fiber, or by making it into a fiber by a double crucible method.

[0031]

EXAMPLES In the table, the column from Bi ₂ O ₃ to BaO shows mol%.
Glasses were prepared by adding the amount of Tm shown by mass percentage in the column of Tm to the matrix glass shown. A _{T g} and the crystallization onset temperature _{T x} which is determined by differential thermal analysis (DTA) are shown in Table (unit: ° C.). Also shown _{H V} for example 1,5 (Unit: MPa).

[0032] In addition, T _x is the temperature to start rising is accompanied by an exothermic peak for crystallization, which is the temperature of the guideline which crystallization starts. T _x -T _g is preferably at 50 ° C. or higher. If the temperature is lower than 50 ° C., there is a possibility of devitrification during fiber processing. More preferably 70 ° C. or higher, particularly preferably 13 ° C.
0 ° C. or higher, most preferably 150 ° C. or higher.

The glass of Example 1 was irradiated with light having a wavelength of 800 nm using a semiconductor laser diode (output: 1 W), and PbS was used as a detector to obtain a wavelength of 1300 to 160.
The emission spectrum at 0 nm was measured. The results are shown in FIG. 1 using the luminescence intensity as an arbitrary unit. Wavelength 1470nm
An emission peak (half-width: 122 nm) due to a transition of Tm from ³ H _{4 to} ³ F ₄ is observed in the vicinity. Therefore, the S ⁺ band (wavelength: 1450 to 1490 nm) and the S band (wavelength:
(1490-1530 nm).

The half width Δλ is 122 nm, which is 76 nm of the Tm-doped fluoride glass exemplified above.
It is larger than 114 nm of Tm-doped tellurite glass.
Therefore, the wavelength width in which gain can be obtained is larger than those of the conventional Tm-doped glass, and the glass is excellent as an optical amplification glass. For Examples 2 to 5, 10 to 13, and 24, Δλ was measured in the same manner. The results are shown in the table (unit: nm).

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

According to the present invention, thermal damage hardly occurs even when a high intensity laser beam is used as the excitation light.
The hardly broken even if the fiber of, and is capable of optical amplification of S ⁺ band and S-band, also wavelength width gain can be obtained a large optical amplifying glass is obtained, wavelengths in the S ⁺ band and S-band Large-capacity information transmission by the multiplex transmission method becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing an emission spectrum of a light amplification glass of the present invention.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Settsuhisa Tabe 3-89 Fukasaku Nishiuracho, Fushimi-ku, Kyoto, Kyoto 1st20A F-term (reference) 4G062 AA04 BB07 CC10 DA01 DA10 DB01 DB02 DB03 DB04 DC01 DD01 DE01 DE02 DE03 DE04 DF01 EA01 EA02 EA03 EA10 EB01 EB02 EB03 EB04 EC01 EC02 EC03 EC04 ED01 ED02 ED03 ED04 EE01 EE02 EE03 EE04 EF01 EF02 EF03 EF01 FE01 FD01 FC03 FD01 FC03 FD01 FC03 FD01 FC03 FD01 FC03 FK01 FL01 FL02 FL03 GA04 GA05 GA06 GA07 GB01 GC01 GD01 GD02 GD03 GD04 GE01 HH01 HH03 HH05 HH06 HH07 HH08 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK03 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05 KK05

Claims (7)

[Claims] 1. The method of claim 1 wherein the matrix glass contains 0.1% by mass.
An optical amplification glass to which Tm of 001 to 10% is added, wherein the matrix glass has a Bi ₂ O ₃ of 15 to 80.
Containing mol%, and an optical amplifying glass containing GeO _2. 2. The matrix glass is Ga₂O₃Or Ce
O₂Containing Bi₂O₃+ GeO ₂+ Ga₂O₃+ C
eO₂Is 70 mol% or more.
Glass. 3. A matrix glass in mole% based on the following _{oxides, Bi 2 O 3 15~80%,} GeO 2 5~80%, Ga 2 O 3 0~30%, CeO 2 0~10%, _{WO 3 0~10%, TeO 2 0~20} %, Al 2 O 3 0~30%, Li 2 O 0~10%, Na 2 O 0~20%, K 2 O 0~20%, ZnO 0~ 20%, MgO 0-20%, CaO 0-20%, SrO 0-20%, BaO 0-20%, TiO ₂ 0-10%, ZrO ₂ 0-10%, SnO ₂ 0-10% The optical amplification glass according to claim 1 or 2, wherein 4. The matrix glass according to claim 1, wherein Bi ₂ O ₃ is 15 to
48 mol%, 15-60 mol% of GeO ₂ , Ga ₂ O ₃
0.5 to 25 mol%, the optical amplification glass according to claim 1, 2 or 3 containing CeO ₂ 0.1 to 0.3 mol%. 5. The matrix glass is composed of SiO ₂ and B ₂ O.
₃ optical amplifying glass according to claim 1, 2, 3 or 4 none containing. 6. The optical amplification glass according to claim 1, wherein the glass transition point is 360 ° C. or higher. 7. The optical amplifier glass according to claim 1, which has a Vickers hardness of 3.6 GPa or more.