JP2001185789A - Light amplifying medium and resin coat light amplifying medium and light amplifier and laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light amplifying medium in which a wide band gain can be obtained in a wavelength area ranging from 1.45 to 1.64 μm, and any thermal damage can be hardly generated. SOLUTION: This light amplifying medium is constituted of a core glass 1 and a clad glass 2, and the core glass 1 is formed by doping Er to a matrix glass by 0.001-10% as mass percentage display, and the matrix glass contains Bi2O3 in the range of 25-70 mol% and at least either B2O3 or SiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the field of 1.45 to 1.6.
The present invention relates to an optical amplification medium capable of amplifying light having a wavelength of 4 μm in a wide band, particularly an optical amplification glass fiber and an optical amplification waveguide.

[0002]

2. Description of the Related Art Research and development of an optical amplifier using a glass fiber having a core doped with a rare earth element as an optical amplifying medium, particularly an Er (erbium) -doped optical fiber amplifier (EDFA) for application to the optical communication field. And its application to optical communication systems is being actively pursued.

On the other hand, in order to cope with 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. Optical amplification glass fibers (EDFs) having an Er-doped optical fiber as a core are being studied for application to WDM. For example, an EDF (silica-based EDF) having an Er-doped silica-based glass fiber and an Er-doped fluoride as a core Glass fiber EDF (fluoride-based EDF) and the like have been conventionally proposed.

[0004]

The conventionally known silica-based EDF has a sharp wavelength dependence of the gain, and the wavelength width at which the gain can be obtained is as narrow as about 10 to 30 nm. As a result, as long as the conventional EDFA is used, the number of wavelength multiplexing channels is limited to about 30 to 40 channels. Further, even in the conventionally known fluoride-based EDF, the wavelength width at which gain can be obtained is about 30 nm, which is also insufficient.
If an EDFA capable of obtaining a gain in a wider wavelength range is realized, the wavelength range of usable signal light is widened and the transmission capacity is remarkably improved. Therefore, the realization of such an EDFA is desired.

In order to solve such a problem, an optical amplifier which can be used in a wide wavelength range by arranging optical amplifiers having different amplification gain characteristics with respect to wavelength in series or in parallel has been proposed, but the structure is complicated. And there is a problem that an area that cannot be amplified exists near the center of the wavelength range.

[0006] An optical amplification medium using telluride oxide glass as a core glass has also been proposed. However, the glass transition point of telluride oxide glass is not high. For example, Optical Materials 3 (199
4) Table 5 and Table 6 of 193 show the glass transition points of various telluride oxide glasses. The maximum value is 343 ° C and the minimum value is 294 ° C.
When the glass transition point is low as described above, the glass may be thermally damaged when a high-intensity laser beam is used as excitation light for optical amplification. The present invention solves the above problems, the wavelength width at which gain is obtained is 40 nm or more,
It is another object of the present invention to provide an optical amplification medium in which the thermal damage hardly occurs.

[0007]

The present invention comprises a core glass and a clad glass, and has a refractive index n ₁ , n ₂ between the core glass and the clad glass for light having a wavelength of 1.55 μm. , 0.0005 ≦ (n ₁ −n ₂ ) /
An optical amplifying medium satisfying a relationship of n ₁ ≦ 0.1, wherein the core glass is glass in which Er is added to the matrix glass by 0.001 to 10% by mass percentage. but the Bi ₂ O ₃ contained in the range of 25 to 70 mol%, and provides an optical amplification medium containing at least one of B ₂ O ₃ and SiO _2. The present invention also provides a resin-coated optical amplification medium in which the optical amplification medium is coated with a resin.

Further, the present invention provides an optical amplifier having an excitation light source and the optical amplification medium or the resin-coated optical amplification medium. Further, the present invention provides a laser device comprising an excitation light source and the optical amplification medium or the resin-coated optical amplification medium.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An optical amplification medium is excited together with signal light.
Light emission is incident. The intensity I of this incident signal light _inAnd optical amplification
The intensity I of the signal light emerging from the medium_outFrom: G = 10 × log_Ten(I_out/ I_in) Is calculated by the gain (unit:
dB). In the present invention, G> 0
Is called "gain is obtained."

The wavelength of the excitation light is usually 0.98 μm
This excites the ⁴ I _11/2 level of Er.
Further, ⁴ of Er in wavelength using an excitation light of 1.48μm
I _13/2 may be to excite the levels may excite higher energy level than ⁴ I _11/2 level by wavelength using a short excitation light than 0.98 .mu.m.

The optical amplification medium of the present invention comprises a core glass and a clad glass covering the core glass, and takes the form of, for example, a glass fiber, a waveguide, or the like. The cross-sectional shape is usually circular when used as a single-mode optical amplification glass fiber, and is usually square or rectangular when used as a single-mode optical amplification waveguide.

FIG. 1 shows an example of the cross-sectional shape of the optical amplification glass fiber, FIG. 2 shows an example in which the cross-sectional shape of the optical amplification waveguide is square, and FIG. Is the case. In each case, the core glass 1 is covered with the clad glass 2.

In the optical amplification glass fiber, the diameter d ₁ of the core glass 1 is preferably ₁ to 12 μm, and the diameter d ₂ of the cladding glass 2 is preferably 40 to 200 μm. If d ₁ is less than ₁ μm, d ₁ / d ₂ becomes too small, and it may be difficult to form a fiber. It is more preferably at least 1.2 μm, particularly preferably at least 2 μm. d
_{If 1} exceeds 12 μm, light having a wavelength of 1.45 to 1.64 μm may not be able to propagate in a single mode. Preferably it is 10 μm or less.

If d ₂ is less than 40 μm, it may be difficult to make a fiber or handle it. Preferably 45
μm or more, particularly preferably 80 μm or more. If d ₂ exceeds 200 μm, the glass fiber may be difficult to bend or may be difficult to handle.
More preferably, it is 150 μm or less. Note that d ₂ is
122-128μm conforming to the standard of optical fiber for communication
It is particularly preferable that the ratio is within the range.

The side length D ₁ of the core glass 1 of the optical amplification waveguide shown in FIG. 2 is ₁ to 12 μm, and the side length D ₂ of the clad glass ₂ is 20 μm.
It is preferable that the thickness be from 200 to 200 μm. D ₁ is 1
If it is less than μm, D ₁ / D ₂ becomes too small, which may make it difficult to manufacture a waveguide, or may make it difficult to connect to another optical component such as an optical fiber. Preferably it is 2 μm or more. When D ₁ is more than 12 μm, 1.45 to
Light having a wavelength of 1.64 μm may not be able to propagate in a single mode. Preferably it is 10 μm or less.

If D ₂ is less than 20 μm, fabrication or handling of the waveguide may be difficult. Preferably 3
0 μm or more. If D ₂ is more than 200 μm, D ₁ / D ₂ becomes too small, and it may be difficult to manufacture a waveguide.
More preferably, it is 150 μm or less.

The length of the long side and the length of the short side of the core glass 1 of the optical amplification waveguide of FIG. 3 are each 1 to 12 μm, and the length of the long side and the length of the short side of the clad glass 2 are any. Is also preferably 20 to 200 μm. Although the center of the core glass 1 and the center of the clad glass 2 coincide in FIG. 2 or FIG. 3, this is not essential. That is, the center of the core glass and the center of the clad glass do not have to coincide with each other.

The following relationship is established between the refractive index n ₁ of the core glass for light having a wavelength of 1.55 μm and the refractive index n ₂ of the cladding glass for light having a wavelength of 1.55 μm. . 0.0005 ≦ (n ₁ −n ₂ ) / n ₁ ≦ 0.1 (n ₁ −n ₂ ) / n ₁ (hereinafter referred to as Δn / n) is 0.0
If it is less than 005, it becomes difficult to confine light in the core glass. Preferably it is 0.001 or more, more preferably 0.003 or more. If it exceeds 0.1, it becomes difficult for light to propagate in the optical amplification medium in a single mode. Preferably it is 0.08 or less, more preferably 0.05 or less.

The refractive index distribution of the cross section of the core glass is not always required to be a uniform distribution, but may be a non-uniform distribution in order to obtain a desired waveguide characteristic. In this case, n ₁ is the maximum value of the refractive index in the cross section of the core glass.

The glass transition point of the core glass is preferably 360 ° C. or higher. The reason is that when a laser beam having a high intensity is used as excitation light for optical amplification, the temperature of the core glass locally increases, and the glass transition point becomes 360 degrees.
If the temperature is lower than 0 ° C., the core glass may be thermally damaged, resulting in an increase in light loss and insufficient light amplification. It is more preferably at least 380 ° C, further preferably at least 400 ° C, particularly preferably at least 410 ° C.

The core glass is obtained by adding Er to the matrix glass, and the amount of Er added is 0.001 to 10% (outer portion) in terms of mass percentage. If it is less than 0.001%, desired optical amplification cannot be obtained. Preferably 0.01
% Or more, more preferably 0.05% or more, particularly preferably 0.1% or more, and most preferably 0.2% or more.
If it exceeds 10%, vitrification becomes difficult, or desired optical amplification cannot be obtained due to concentration quenching. It is preferably at most 8%, more preferably at most 5%. E in core glass
The concentration distribution of r may be uniform, but may be such that the Er concentration in the central portion of the core glass becomes high in order to efficiently use the portion where the intensity of the excitation light is high for the excitation of Er.

In order to improve the excitation efficiency and the concentration quenching characteristics, Yb may be added to the matrix glass up to 0.08% by mass percentage (outer portion).
If it exceeds 0.08%, there is a risk of devitrification during molding. More preferably, it is 0.04% or less. When Yb is added, the addition amount is preferably 0.01% or more. It is more preferably at least 0.04%.

The composition of the matrix glass and the cladding glass is determined so as to satisfy the above relationship between n ₁ and n ₂ , but it is preferable that the compositions of the two are almost the same. It should be noted that if the compositions of both are exactly the same, n
_{Since the} relationship between ₁ and n ₂ does not hold, the compositions of both must be different.

The matrix glass contains 25% Bi ₂ O ₃ .
It is contained in the range of -70 mol%. If it is less than 25 mol%, desired optical amplification, that is, desired broadband amplification characteristics cannot be obtained. Preferably 30 mol% or more, more preferably 38%
That is all. If it exceeds 70 mol%, vitrification becomes difficult.
Or, devitrification occurs during molding, or the glass transition point is too low. It is preferably at most 60 mol%, more preferably at most 55 mol%, particularly preferably at most 48 mol%.

The matrix glass is composed of B ₂ O ₃ and S
It contains at least one of iO ₂ . In this case, it may not contain contain only B ₂ O ₃ and SiO _2, may contain no B ₂ O ₃ and containing only SiO _2, both B ₂ O ₃ and SiO ₂ May be contained. B ₂
If neither O ₃ nor SiO ₂ is contained, vitrification becomes difficult.

The matrix glass is substantially as follows: Bi ₂ O ₃ : 25 to 70% in terms of mol% based on oxide, and B ₂ O <sub>3
+ SiO 2: 5~75%, CeO</sub> 2: 0~10%, Al 2
O ₃ + Ga ₂ O ₃ : 0 to 30%, ZnO + TeO ₂ + BaO
+ WO ₃ : preferably from 0 to 40%. Similarly, for the clad glass, the following oxide-based mol%
Substantially in the _{display, Bi 2 O 3: 25~70%} , B 2 O 3 + S
_{iO 2: 5~75%, CeO 2} : 0~10%, Al 2 O 3 +
Ga ₂ O ₃ : 0 to 30%, ZnO + TeO ₂ + BaO + W
O ₃ : 0 to 40%. This preferred composition common to the core glass and the clad glass will be described below, where mol% is simply expressed as%.

Since Bi ₂ O ₃ has been described above, it will not be described here. However, the content of Bi ₂ O ₃ in the clad glass was 2
The reason why the content is preferably 5% or more is that if the content is less than 25%, the Bi ₂ O ₃ content of the matrix glass of the core glass becomes too small, and there is a possibility that desired optical amplification cannot be obtained.

B ₂ O ₃ and SiO ₂ are network formers and contain at least one of them. If the total amount is less than 5%, vitrification becomes difficult or devitrification occurs during molding. It is preferably at least 20%, more preferably at least 25%, particularly preferably at least 30%, most preferably at least 40%. If the total amount is more than 75%, devitrification occurs during molding. It is preferably at most 70%, more preferably at most 65%, particularly preferably at most 60%.

CeO ₂ is not essential, but has an effect of preventing Bi ₂ O ₃ in the glass composition from precipitating as metallic bismuth during melting of the glass and lowering the transparency of the glass. May be. If it exceeds 10%, vitrification may be difficult. It is more preferably at most 5%, particularly preferably at most 1%. When CeO ₂ is contained, the content is more preferably 0.01% or more, particularly preferably 0.05% or more, and most preferably 0.1% or more.

In addition, when CeO ₂ is contained, yellow or orange coloring becomes strong and the transmittance of the glass decreases,
The background loss at the pump light wavelength (for example, 0.98 μm) or the signal light wavelength may increase. In this respect, the content of CeO ₂ is preferably less than 0.15%, and particularly preferably substantially no content.

Al ₂ O ₃ is not essential, but has an effect of suppressing devitrification during molding, and may be contained up to 20%. If it exceeds 20%, transparency may decrease due to devitrification. More preferably 15% or less, particularly preferably 11% or less.
% Or less. When Al ₂ O ₃ is contained, the content is more preferably 0.1% or more, particularly preferably 1% or more, and most preferably 2% or more.

Although Ga ₂ O ₃ is not essential, it has an effect of suppressing devitrification at the time of molding in addition to increasing the wavelength width at which gain can be obtained, and may be contained in a range of up to 20%. If it exceeds 20%, transparency may decrease due to devitrification. It is more preferably at most 18%, particularly preferably at most 15%, most preferably at most 10%. When Ga ₂ O ₃ is contained, the content is more preferably 0.1% or more, particularly preferably 1% or more, and most preferably 2% or more.

The total content of Al ₂ O ₃ and Ga ₂ O ₃ is 30
% Is more preferable. If it exceeds 30%, transparency may decrease due to devitrification. It is more preferably at most 25%, particularly preferably at most 20%, most preferably at most 15%. When at least one of Al ₂ O ₃ and Ga ₂ O ₃ is contained, the total content of both is more preferably 2% or more, particularly preferably 4%.
That is all.

Although ZnO, TeO ₂ , BaO and WO ₃ are not essential, they are used to adjust the physical properties (refractive index, thermal expansion coefficient, etc.) of the core glass and the clad glass and to facilitate vitrification. May be contained in the total content of up to 40%. It is more preferably at most 20%, particularly preferably at most 10%.

In a preferred embodiment of the present invention,
The matrix glass and / or the clad glass substantially consist of the above components, but the other components are added in a total amount of 10%.
% Or less. For example, to suppress devitrification during molding or to facilitate vitrification,
BeO, MgO, CaO, SrO, Li 2 O, Na 2 O,
K ₂ O, Cs ₂ O, La ₂ O ₃ , TiO ₂ , ZrO ₂ , Cd
O, In ₂ O ₃ , GeO ₂ , PbO, and the like may be contained.

The compositions of the core glass and the cladding glass are preferably determined not only to satisfy the above relationship between n ₁ and n ₂ , but also to match the coefficients of thermal expansion of both.

In the optical amplifying medium of the present invention, 1.45 to 1.45.
The wavelength width at which gain can be obtained for light having a wavelength of 1.64 μm is preferably 40 nm or more. If it is less than 40 nm, the number of channels in WDM may be too small. The wavelength width is more preferably 50 nm or more,
Particularly preferably 60 nm or more, most preferably 80 nm
That is all.

The resin-coated optical amplifying medium of the present invention is obtained by coating the optical amplifying medium of the present invention with a resin in order to increase the breaking strength. The thickness of the resin is preferably in the range of 2 to 400 μm. If it is less than 2 μm, the effect of increasing the breaking strength may not be obtained. It is more preferably at least 3 μm, particularly preferably at least 8 μm. 40
If it exceeds 0 μm, uniform resin coating may be difficult. More preferably, it is 70 μm or less.

The resin is not particularly limited as long as it has good adhesion to the clad glass and can be easily coated on the clad glass. In order to suppress the propagation of cladding mode of light, the refractive index of the resin is preferably larger than that of the cladding glass, and 1.45.
It is preferable that the resin has a large absorption coefficient for light having a wavelength of about 1.64 μm.

The Young's modulus of the resin is preferably 1 MPa or more. If it is less than 1 MPa, the resin may be easily damaged, and the breaking strength may not be increased. More preferably 4.9 MPa or more, particularly preferably 98 MPa
a or more. Examples of the resin include a thermosetting silicone resin, a UV curable silicone resin, an acrylic resin, an epoxy resin, and a polyimide resin.

The optical amplifying medium of the present invention is manufactured, for example, as follows. The raw materials are mixed and placed in a platinum crucible, an alumina crucible, a quartz crucible or an iridium crucible,
The glass for core and the glass for cladding are produced by melting in air at 00 to 1300 ° C. and casting the obtained melt in a predetermined mold.

When manufacturing an optical amplification glass fiber,
Next, the glass for the core and the glass for the clad are stacked and 400
Extrusion molding at ~ 500 ° C to produce a preform having a core / cladding structure. When producing an optical amplification waveguide, the core glass is formed in a rectangular parallelepiped shape, and the core glass is inserted into a cladding glass having a hole to be fitted with the core glass, thereby producing a preform having a core / clad structure. I do. The preform thus obtained is placed in an electric furnace at about 500 ° C. to be softened and molded while controlling to have a desired size to obtain an optical amplification medium.

A buried optical amplification waveguide as shown in FIG. 4 is manufactured, for example, as follows. Si,
Substrate 10 such as a semiconductor substrate such as GaAs or a quartz glass substrate
A clad glass film 12A is formed on the surface of the substrate by an electron beam evaporation method, a CVD method, a sputtering method, or the like.

Next, a core glass film is formed on the surface of the clad film 12A by an electron beam evaporation method, a CVD method, a sputtering method, or the like. The core glass film is processed by a photolithography method and a dry etching method to produce a core glass 11 having a rectangular or square cross section. Examples of the etching gas used in the dry etching method include CHF ₃ gas, CHCl ₃ gas, a mixed gas of CHF ₃ gas and CHCl ₃ gas, and the like.

Finally, the clad glass film 12A and the core glass 11 are covered with a clad glass film 12B having the same refractive index as the clad glass film 12A. This coating is performed by, for example, an electron beam evaporation method, a CVD method, or a sputtering method. The clad glass in the buried optical amplification waveguide includes a clad glass film 12A and a clad glass film 12B.

The resin-coated optical amplifying medium of the present invention is produced, for example, by coating the optical amplifying medium obtained by the above-mentioned molding with a UV-curable resin and then performing UV irradiation. Alternatively, the optical amplification medium obtained by the molding may be coated with a thermosetting resin and then heated to 50 to 200 ° C. to produce the medium.

The optical amplifying medium of the present invention and the resin-coated optical amplifying medium of the present invention are suitably used for optical amplifiers, laser devices and the like. An example of such an optical amplifier is a WDM-compatible optical amplifier. Hereinafter, the light amplifying medium of the present invention and the resin-coated light amplifying medium of the present invention are collectively referred to as a light amplifying body of the present invention.

In the optical amplifier according to the present invention, the pump light from the pump light source is incident on the optical amplifier according to the present invention.
The signal light input to the optical amplifier of the present invention is amplified. The optical amplifier of the present invention generally includes a signal light input device, a multiplexing device for multiplexing signal light and pump light, and a demultiplexer of signal light and pump light, in addition to the pump light source and the optical amplifier of the present invention. It has a demultiplexer and a signal light output device. Both the signal light input device and the pump light source are connected to a multiplexer, and the multiplexer is connected to one end of the optical amplifier of the present invention. Further, a demultiplexer is connected to the other end of the optical amplifier of the present invention, and the demultiplexer is connected to a signal light output device.

The optical amplifier of the present invention to which the signal light source is connected has, for example, the following configuration A. The signal light source is connected to an optical isolator by an optical connector (signal light input device), and is connected to a multiplexing optical coupler (multiplexing device) via the optical isolator. An excitation light source is also connected to the optical coupler. The optical coupler is connected to one end of an optical amplification glass fiber. The other end of the optical amplification glass fiber is connected to an optical isolator via a demultiplexing optical coupler (demultiplexing device). The optical isolator is connected to an optical connector (signal light output device). Each component is connected by an optical fiber.

It is preferable that the connection between the optical amplification glass fiber and the optical fiber be made via an enlarged core fiber between them. The connection between the optical amplification glass fiber and the expanded core fiber is preferably performed by fusion or adhesion, and the connection between the expanded core fiber and the optical fiber is preferably performed by fusion. The core-expanded fiber here is a fiber for connecting optical fibers having different core diameters.

In the configuration A, the forward pumping system is adopted. However, the optical amplifier in the present invention is not limited to this, and a backward pumping system or a bidirectional pumping system may be adopted.

In the laser device of the present invention, the optical amplifier of the present invention in a state where the excitation light from the excitation light source is incident functions as an optical amplification element, and laser oscillation occurs. The laser device of the present invention has a device for feedback coupling light having a resonance frequency to the optical amplifier of the present invention, in addition to the excitation light source and the optical amplifier of the present invention.

The laser device of the present invention has, for example, the following configuration. The excitation light source is connected to the optical coupler. Light that has passed through a narrow band-pass filter described later is also input to the optical coupler. The optical coupler is connected to one end of an optical amplification glass fiber. The other end of the optical amplification glass fiber is connected to an optical isolator. Then, the light that has passed through the optical isolator is guided to the narrow band pass filter, and again to the optical coupler as described above. That is, a ring-shaped optical resonator is formed by the optical coupler, the optical amplifier, the optical isolator, and the narrow band-pass filter. Laser light is extracted from the output end of the optical coupler. Each component is connected by an optical fiber. In addition, a portion of the ring-shaped optical resonator excluding the optical amplifier corresponds to the feedback coupling device.

[0054]

EXAMPLES Core glass and cladding glass having the compositions shown in the columns from Bi ₂ O ₃ to Er in the table were produced. “B + Si” in the table is the total amount of B ₂ O ₃ and SiO ₂ , and “Al + G”
“a” is the total amount of Al ₂ O ₃ and Ga ₂ O ₃ , “ZnTeBaW”
Is the total amount of ZnO, TeO ₂ , BaO and WO ₃ . The column from Bi ₂ O ₃ to “ZnTeBaW” is mol%.
The display and Er are the outer mass% display.

For these glasses, the glass transition point T _g
Was measured by differential thermal analysis (DTA). T
Shown in the column of _g (unit: ° C.). Note that those marked with * are estimated values obtained by calculation from the composition. Further, the refractive index of these core glass and cladding glass with respect to light having a wavelength of 1.55 μm was measured by an ellipsometer. The results are shown in columns n ₁ and n ₂ of the table, and the value of (n ₁ −n ₂ ) / n ₁ is shown in the column of Δn / n. Note that those marked with * are estimated values obtained by calculation from the composition.

In Examples 1 to 3, a preform having a core / cladding structure was prepared from the core glass and the cladding glass, and 525 ° C. was prepared based on the preform.
The fiber processing was performed to produce a glass fiber. Table 1
In the column of diameter, the diameters of the core glass and the clad glass are shown (unit: μm).

In Example 1, the glass fiber was further coated with a UV-curable acrylic resin.
V irradiation was performed to produce a resin-coated glass fiber having a diameter of 250 μm. The thickness of the resin is 62.5 μm. Also,
The Young's modulus of the resin is 1130 MPa.

The resin-coated glass fiber having a length of 6 cm was prepared, and light having a wavelength of 1.50 to 1.59 μm (signal light: 0.001 mW) and excitation laser light (50 mW) having a wavelength of 0.975 μm were combined. Light synthesized by the wave device was incident on the resin-coated glass fiber. From the intensity of the signal light exiting the resin-coated glass fiber and the intensity of the incident signal light,
The gain of this resin-coated glass fiber was calculated. The gains (unit: dB) for light having wavelengths of 1.50, 1.53, 1.56, and 1.59 μm are 10 and 1, respectively.
6, 14, and 9. That is, 1.50 to 1.59
It was confirmed that gain could be obtained in the wavelength range of μm, and the wavelength width in which the gain was obtained was 0.09 μm or more (90 nm or more).
It turned out to be.

Examples 4 to 10 are examples of a combination of a core glass and a cladding glass suitable as an optical amplification glass fiber. That is, in Examples 4 to 10, Δn / n
Not only the above relationship is satisfied, but also the coefficient of thermal expansion is matched.

Further, a buried optical amplification waveguide made of the core glass and the cladding glass of Example 11 as shown in FIG. 4 was produced by using an electron beam evaporation method and a dry etching method. The length of the long side and the length of the short side of the core glass of the optical amplification waveguide are 8 μm and 10 μm, respectively, and the length of the long side and the length of the short side of the clad glass are 40 μm respectively.
m, 140 μm.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

The optical amplification fiber of Example 1 (length: 15 cm)
Using the optical amplification fiber of Example 10 (length: 10 cm), an optical amplifier having the configuration A was manufactured. In each optical amplifier, the intensity is 100 mW and the wavelength is 0.98.
μm excitation light and intensity 1 mW, wavelength 1.50 to 1.59 μ
When the signal light of m was incident, the intensity of the output / signal light was 10 mW or more.

With respect to the optical amplifier using the optical amplification fiber of Example 10, a signal light having a wavelength of 1.45 to 1.64 μm was further incident, and the gain G was measured. As a result, 1.45
G for light with a wavelength of １1.64 μm was positive.

The optical amplification waveguide of Example 11 (length: 5c
Using m), an optical amplifier having the configuration A was manufactured. In this optical amplifier, the intensity is 100 mW, and the wavelength is 0.
Excitation light of 98 μm, intensity 1 mW, wavelength 1.50 to 1.6
When a signal light of 0 μm was incident, the intensity of the output / signal light was 10 mW or more at a wavelength of 1.53 to 1.6 μm. Further, a signal light having a wavelength of 1.45 to 1.64 μm was incident, and the gain G was measured. As a result, 1.45
G was positive for light at a wavelength of 1.64 μm.

The optical amplification fiber of Example 1 (length: 8c
m) and a laser device using the optical amplification fiber of Example 3 (length: 20 cm), and performing a laser oscillation experiment while changing the transmission band of the narrow band-pass filter in the range of 1.50 to 1.59 μm. Was. Intensity 100 mW, wavelength 0.
When the excitation light of 98 μm was incident, 1.50 to 1.5
Laser oscillation was confirmed in a wide wavelength range of 9 μm.

[0069]

According to the present invention, 1.45 to 1.64 .mu.m.
A broadband gain can be obtained in the wavelength range of m, and an optical amplification medium that is less likely to be thermally damaged by the pump light can be obtained. Further, a resin-coated optical amplification medium having a high breaking strength can be obtained. With the WDM-compatible optical amplifier using this optical amplification medium, the number of wavelength division multiplexing channels in WDM can be increased. Further, by a laser device using this optical amplification medium, 1.50-1.
Laser oscillation becomes possible in a wide wavelength range of 59 μm.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a cross-sectional shape of an optical amplification glass fiber.

FIG. 2 is a diagram illustrating an example of a cross-sectional shape of an optical amplification waveguide.

FIG. 3 is a diagram illustrating an example of a cross-sectional shape of an optical amplification waveguide.

FIG. 4 is a sectional view of a buried optical amplification waveguide.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Senoo Tomo Exhibition 1-8, Machiikedai, Koriyama-shi, Fukushima Pref. 1-8 Koriyama West Second Industrial Park Asahi Glass Koriyama Electric Materials Co., Ltd. F-term (reference) 2H047 KA04 QA04 RA08 TA13 2H050 AB07Z AB09Z AB17Z AB18Z AD16 5F072 AB09 AK03 AK06 FF02 FF03 JJ20 RR01 YY17

Claims (6)

[Claims] 1. A material comprising a core glass and a clad glass, wherein between the refractive indices n ₁ and n ₂ of the core glass and the clad glass with respect to light having a wavelength of 1.55 μm, 0.0005 ≦ (n ₁ −n ₂ ) / n ₁ ≦ 0.1, wherein the core glass is glass in which Er is added to the matrix glass in a mass percentage of 0.001 to 10%. There, the matrix glass, a Bi ₂ O ₃ contained in the range of 25 to 70 mol%, and, B ₂ O ₃ and the optical amplification medium, characterized in that it contains at least one of SiO _2. 2. The matrix glass is substantially composed of 25 to 70% of Bi ₂ O ₃ , 5 to 75% of B ₂ O ₃ + SiO ₂ , 0 to 10% of CeO ₂ , _2. The optical amplification medium according to claim 1, comprising 0 to 30% of ₂ O ₃ + Ga ₂ O _{3 and} 0 to 40% of ZnO + TeO ₂ + BaO + WO ₃ . Wherein the cladding glass is substantially in mole% based on the following _{oxides, Bi 2 O 3 25~70%,} B 2 O 3 + SiO 2 5~75%, CeO 2 0~10%, Al _3. The optical amplification medium according to claim 1, comprising 0 to 30% of ₂ O ₃ + Ga ₂ O _{3 and} 0 to 40% of ZnO + TeO ₂ + BaO + WO ₃ . 4. A resin-coated optical amplifying medium obtained by coating the optical amplifying medium according to claim 1, 2 or 3 with a resin. 5. An optical amplifier comprising: an excitation light source; and the optical amplifying medium according to claim 1, 2 or 3, or the resin-coated optical amplifying medium according to claim 4. 6. A laser device comprising an excitation light source and the optical amplification medium according to claim 1, 2 or 3, or the resin-coated optical amplification medium according to claim 4.