JPH08110535A - Light amplifying medium, light amplifier using the medium and laser device - Google Patents

Abstract

PURPOSE: To operate in a wide wave band by forming an optical fiber with an oxide-tellulide glass added with erbium and forming a core with the optical fiber. CONSTITUTION: An amplifying optical fiber with the core as an oxide-tellulide glass mixed with erbium is used as a light amplifying medium, a signal light source 1 and an excitation light source 2 are connected to one end of the fiber through an optical coupler 3, an optical isolator 5 is connected to the other end, and the components are connected with an optical fiber 6 to constitute a light amplifier. For example, a TeO2 (77mol%)-Na2 O(6mol%)-ZnO(15.5mol%)-Bi2 O3 (1.5mol%) glass is used as the core material, and Er is added by 1000ppm to form an optical fiber 4 which is used as the light amplifying medium. Further, 0.98μm is selected as the excitation wavelength, and a DFB laser is used as the signal light source. Consequently, an amplification gain is obtained with the wavelength between 1.6μm and 1.7μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplification medium, an optical amplifier and a laser device using the same, and
The present invention relates to a broadband optical amplification medium that can operate even in a wavelength range of 6 μm to 1.7 μm, an optical amplifier and a laser device using the same.

[0002]

2. Description of the Related Art In operating an optical communication system,
In addition to the signal light, light is required to maintain and monitor the system. For example, in the 1.55 μm band optical communication system, maintenance and monitoring by light in the wavelength band of 1.6 μm to 1.7 μm are considered, and therefore development of a light source and an optical fiber amplifier in this wavelength band is desired. ing.

In recent years, for the purpose of application to the optical communication field,
Research and development of an Er (erbium) -doped optical fiber amplifier (EDFA), which uses an optical fiber having a core doped with a rare earth element as an optical amplification medium, has been promoted, and its application to an optical communication system has been actively promoted. .

In particular, research has been conducted on an optical communication system using wavelength division multiplexing for expanding the transmission capacity in order to cope with the diversification of communication services expected in the future. The characteristic required for the EDFA used in this wavelength division multiplexing transmission system is that the fluctuation of the amplification gain due to the signal wavelength is small. This is because if the signals are relayed and amplified in multiple stages by the EDFA, there will be a difference in intensity level between the signals and it will not be possible to transmit with uniform characteristics over all wavelengths in use. Therefore,
Currently, research is being conducted on EDFAs whose gain is flat with respect to wavelength.

In the case of an Er-doped silica optical fiber, the wavelength dependence of the gain is sharp (the unevenness of the gain is severe), and in order to correct this, a filter or the like is inserted in the EDFA to flatten the gain. There is. However, the wavelength width where the gain is flat is as narrow as about 10 nm.

An Er-doped fluoride fiber is known as one having a wide wavelength region with a relatively flat gain. However, the wavelength width with a very flat gain is limited to about 30 nm.

If an EDFA having a flat gain characteristic in a wider wavelength range can be realized, the usable signal wavelength can be widened and the transmission capacity can be remarkably improved. Therefore, the realization of such an EDFA is desired.

If a tunable laser light source in a wide wavelength range is started, it can be used as a light source for wavelength division multiplexing transmission, and can be applied to increase communication capacity. Therefore, such an EDFA can be realized. Is desired.

[0009]

However, there is no optical fiber amplifier that operates in the wavelength band of 1.6 μm to 1.7 μm so far.

In view of such circumstances, the present invention has an object to provide an optical amplification medium which has a wide amplification wavelength band and operates from a wavelength band of 1.6 μm to 1.7 μm, and an optical amplifier and a laser device using the same. And

An object of the present invention is to improve the characteristics of a conventional EDFA in which the amplification gain becomes flat only in a narrow wavelength range, and to provide an EDFA having a high amplification efficiency in a wide wavelength range with high quantum efficiency and low noise. That is.

An object of the present invention is to improve the characteristics of a conventional EDFA in which the amplification gain is flat only at a narrow wavelength,
It is to provide an EDFA and a high-bandwidth tunable laser whose amplification gain is flat in a wide wavelength range.

[0013]

According to a first aspect of the present invention for achieving the above object, in an optical amplifying medium having at least a core made of a glass to which a rare earth element is added, the glass is erbium. An optical amplifying medium characterized by being an oxide telluride glass to which is added.

A second aspect of the present invention is an optical amplification medium in which at least a core is formed of a glass to which a rare earth element is added, and the glass is an telluride oxide glass to which erbium and ytterbium are added. The optical amplification medium is characterized in that

A third aspect of the present invention is the optical amplifying medium according to the first or second aspect of the present invention, wherein the oxidized telluride type glass contains at least one of boron, phosphorus or a hydroxyl group. It is in.

According to a fourth aspect of the present invention, the optical amplification medium according to any one of the first to third aspects of the present invention, and pumping light and signal light for exciting the optical amplification medium are input to the optical amplification medium. The optical amplifier is characterized by comprising:

A fifth aspect of the present invention is an optical resonator having at least a portion of the optical amplification medium according to any one of the first to third aspects of the present invention, and an excitation light source for exciting the optical amplification medium. A laser device characterized by comprising:

A sixth aspect of the present invention is an optical amplifier in which a plurality of optical amplifying media made of an optical fiber having at least a core doped with erbium are arranged in series, and at least one of the optical amplifying media has the first aspect of the present invention. An optical amplifier using the optical amplifying medium according to any one of the third to third aspects.

According to a seventh aspect of the present invention, in a laser device in which a plurality of optical amplifying media made of optical fibers having at least a core doped with erbium are arranged in series, at least one of the optical amplifying media has the first aspect of the present invention. A laser device using the optical amplifying medium according to any one of the third to third aspects.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The present invention, used as an optical amplification medium fiber using an oxidizing Telluride based glass doped with Er (erbium), derived from ⁴ I _13/2 level of Er to ⁴ I _15/2 level The most main feature is to use the emission transition. FIG. 6 is an energy level diagram of Er ³⁺ ions, which shows the upper level ⁴ I
Shows that emits light by transition to the same lower level ⁴ I _15/2 and defined state from _13/2.

FIG. 7 shows Er in telluride oxide glass.
Is ⁴ compares the emission of I _13/2 → ^{4 4} I of Er ³⁺ emitting and fluoride glass of the I _{15/2 13/2} → ⁴ I _15/2 ^3+.

The emission of ⁴ I _13/2 → ⁴ I _{15/2 of} Er ³⁺ is _wider in fluoride glass than in other glasses such as quartz glass ⁴ I _13/2 → ⁴ I _15/2 It is known to have an emission band. However, as can be seen from FIG.
Even if the Er is present in the fluoride glass, it is difficult to perform optical amplification or laser oscillation at a long wavelength of 1.6 μm or more, since it does not emit light at a wavelength longer than 6 μm.

However, when Er is added to an oxide telluride type glass, it is subjected to a stronger electric field than other glasses, and as a result, due to the Stark effect of the ⁴ I _13/2 and ⁴ I _15/2 levels, etc. The level spread becomes large and it has a stimulated emission cross section even in the longer wavelength region, which is 1.65μ as seen in Fig. 7.
Fluorescence is present even at long wavelengths of m or longer.

Therefore, if an oxide telluride glass fiber in which Er is added to at least the core is used as the optical amplification medium, the light from 1.6 μm to 1.7 μm, which cannot be realized by the Er-doped quartz fiber or the Er-doped fluoride fiber, is obtained. Amplification and laser oscillation are possible. When the oxidized telluride-based glass contains at least one of boron, phosphorus and a hydroxyl group, the gain coefficient and the noise figure are improved even when excited by 0.98 μm. That is, B-O, P
Vibrational energies of -O and OH are about 1400c, respectively.
m ^-1, 1200cm ^-1, a 3700 cm ^-1, since the phonon energy of oxidation telluride glass containing no these are 600~700cm ^-1, increased more than double. Therefore, when the wavelength is near 0.98 μm, Er ⁴ I
_11/2 for level directly excited to ⁴ I _13/2 → ⁴ I _15/2 lowering of easily quantum efficiency undergo relaxation by Taotoko release the cause optical amplification of 1.5μm by transition is small, ⁴ This is _because the excitation efficiency of the I _13/2 level is unlikely to decrease (FIG. 7). Also, ⁴
Likely to occur relief from the I _11/2 level to the ⁴ I _13/2 level and ⁴ I
_Rather than directly exciting the _13/2 level with light near 1.48 _μm
⁴ I _11/2 inversion is easy to obtain among those who excites the ⁴ I _13/2 level After exciting level is ⁴ I _13/2 level position and ⁴ I _15/2 level, thus also the noise characteristics Because it is excellent.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Example 1 TeO ₂ (77 mol%)-N
a ₂ O (6 mole%) - ZnO (15.5 mol%) - Bi
₂ O ₃ (1.5 mol%) glass as core material and Er of 1
000 ppm was added, and TeO ₂ (75 mol%)-Na _{2 was} added.
O (5 mol%)-ZnO (20 mol%) glass was used as a clad material to form an optical fiber having a cutoff wavelength of 0.95 μm and a core-clad refractive index difference of 2%, which was used as an optical amplification medium. Using this optical amplification medium, 1.6 μm to 1.
An optical amplifier having a wavelength band of 7 μm was prepared and an amplification experiment was conducted. 0.98 μm was selected as the excitation wavelength, and a DFB laser was used as the signal light source in the 1.6 μm to 1.7 μm band.

FIG. 1 is a block diagram of this embodiment. The signal light source 1 and the pumping light source 2 are connected to one end of an amplification optical fiber 4 via an optical coupler 3 and the other end of the amplification optical fiber 4 is connected. Is connected to the optical isolator 5. The optical fibers 6 are used to connect the respective parts.

By an amplification experiment using the optical amplifier of this configuration, an amplification gain could be obtained at a wavelength between 1.6 μm and 1.7 μm.

Further, the same optical amplification medium was used to construct a ring laser having a tunable narrow band pass filter shown in FIG. Such a ring laser is shown in FIG.
Instead of the signal light source 1, the output side of the optical isolator 5 is connected to the optical coupler 3 to form a ring-shaped optical resonator, and the narrow bandpass filter 7 is inserted in the middle of the ring-shaped optical resonator. It is a thing. Then, the transmission band of the narrow bandpass filter 7 was varied between 1.6 μm and 1.7 μm, and light was emitted from the excitation light source 2 to perform a laser oscillation experiment. As a result, laser oscillation in the above wavelength band could be confirmed from the output end 8.

In the above embodiment, the excitation wavelength is 0.98.
⁴ I _11/2 level was excited using 1 μm, but 1.48 μm
It goes without saying that the ⁴ I _13/2 level may be directly excited by using the band wavelength. Further, light having a wavelength shorter than 0.98 _μm may excite the energy level higher than the ⁴ I _11/2 level.

Example 2 Using the optical amplifier having the configuration shown in FIG. 1, an optical amplification experiment in the 1.5 μm band was conducted. The excitation wavelength was 0.98 μm. As a result, in the short wavelength region, the gain cannot be obtained with the usual Er-doped fiber amplification width.
The gain could be confirmed even at 7 μm. As a result, it was confirmed that the gain can be obtained in a wide range of wavelength width of 160 nm or more.

[Embodiment 3] Er and Yb instead of Er
An optical fiber similar to that of Example 1 was manufactured except that the glass co-doped with was used as the core, and the optical fiber was used.

Using this optical amplification medium, an optical amplification experiment and a laser oscillation experiment were conducted with the configurations of Example 1 and Example 2. 1.029 μm as excitation wavelength (Yb-added YAG
Laser), 1.047 μm (Nd-doped YLF laser),
1.053 μm (Nd-doped YAG laser), 1.064
(Nd-added YAG laser) or the like was used. Thus Yb
When Er is co-doped with Er, gain of energy transfer from Yb to Er allows laser oscillation between 1.6 μm and 1.7 μm and excitation of 1.5 μm band even when excited at the wavelength as described above. Wideband optical amplification could be confirmed.

In the above embodiments, an example of the composition of the optical fiber is shown, but the present invention is not limited to this. For example, Cs ₂ O, Rb ₂ O, K ₂ O, Na ₂
O, Li ₂ O, BaO, SrO, CaO, MgO, Be
O, La ₂ O ₃ , Y ₂ O ₃ , Sc ₂ O ₃ , Al ₂ O ₃ ,
ThO ₂ , HfO ₂ , ZrO ₂ , TiO ₂ , Ta ₂
O ₅ , Nb ₂ O ₅ , WO ₃ , Tl ₂ O, CdO, Zn
It may be a glass containing at least one of O, PbO, In ₂ O ₃ , Ga ₂ O ₃ , and Bi ₂ O ₃ together with TeO ₂ (see: Glass Handbook (Eighth Edition), Sakubana Sachio et al. Edited by Asakura Shoten, published in 1975). Also, Er
Alternatively, Er and Yb may be added not only to the core but also to the clad.

Further, the optical amplifier is not limited to the above-mentioned structure as long as it has the optical amplification medium of the present invention, a pumping light source for exciting the optical amplification medium, and input / output means for signal light. Absent.

Further, if the laser device has a pumping light source for inserting the optical amplifying medium of the present invention in the middle of an optical resonator formed of an optical fiber and further exciting the optical amplifying medium, It is not limited.

[Embodiment 4] Er1 as an amplifying fiber
The amplification characteristic in the 1.5 μm band was measured using 4 m of the fiber in which 000 ppm was added to the core. The core glass composition is TeO ₂ (75 mol%)-ZnO (13 mol%)-Na
₂ O (3 mol%)-Bi ₂ O ₃ (4 mol%)-P ₂ O ₅
Phosphorus is added as (5 mol%), and the cladding glass composition is TeO ₂ (75 mol%)-Na ₂ O (5 mol%)-Z.
nO (20 mol%). The core / clad refractive index difference was 2%, and the cutoff wavelength was 0.96 μm.
When a small signal gain in the 1.5 μm band was measured by using 0.98 μm light (semiconductor laser as a light source) as pumping light, the gain efficiency was increased by 5 times as compared with the one without phosphorus, and the gain was 2 dB.
/ MW has been reached. Also, when the gain spectrum in the saturation region was measured with the input signal level set to 0 dBm,
The gain became flat in the width of 70 mm from 30 nm to 1600 nm (excitation intensity was 100 mW). By adding phosphorus as the core glass in this way,
The gain coefficient and noise figure are greatly improved.

The noise figure was 7 dB when phosphorus was not added, but was lowered to 4 dB by adding phosphorus.

It was also confirmed that the gain coefficient and the noise figure were improved by adding B ₂ O ₃ instead of P ₂ O ₅ .

Example 5 TeO ₂ (77 mol%)-Z
nO (13 mole%) - Na ₂ O (6 mole%) - Bi ₂ O
₃ (4 mol%) was used as the core glass and 50 OH groups were added to it.
It was confirmed that when 00 ppm and Er of 1000 ppm were added, the gain coefficient increased three times as compared with the case where no OH group was added.

The degree of increase in the gain coefficient is lower than that when phosphorus is added because the vibration energy of the OH group is 3700 cm.
^Since it has a large value of ^-1 , ⁴ I, which is the initial level of amplification
_This is because the _13/2 level is also slightly relaxed by multiphonon emission.

Example 6 In Examples 1 and 2, the effect of adding boron, phosphorus and OH groups was shown using TeO ₂ —ZnO—Na ₂ O—Bi ₂ O ₃ based glass as the core glass. However, the effect of adding these elements is not limited to the above-mentioned oxide telluride glass. For example, TeO ₂
-BaO-Na ₂ O-based, TeO ₂ -BaO-K ₂ O system,
TeO ₂ -BaO-CaO system, TeO ₂ -BaO-Sr
O system, TeO ₂ -SrO-CaO system, TeO ₂ -Li ₂
O-Na _{2 O-based, TeO 2 -Li 2 O-K} 2 O -based, Te
_{O 2 -Li 2 O-BaO-} CaO-SrO system, TeO _{2
-La 2 O 3 -Li 2 O-} K 2 O-N 2 O system, TeO ₂
-La ₂ O ₃ -BaO-SrO system, TeO ₂ -MgO-
_{K 2 O-Li 2 O-} N 2 O system, TeO ₂ -MgO-Ba
O-SiO-CaO _{system, TeO 2 -MgO-La 2 O} 3
-Al ₂ O _{3 system, TeO 2 -ThO 2 -K 2 O} -Li 2
O-Na ₂ O-based, TeO ₂ -ThO ₂ -BaO-SrO
System, TeO ₂ —ThO ₂ —MgO—BeO system, TeO _{2
-ThO 2 -La 2 O 3 -Al 2} O 3 system, TeO ₂ -B
_{eO-K 2 O-Li 2} O-N 2 O system, TeO ₂ -BeO
-MgO-CaO-BaO-SrO system, TeO ₂ -Be
_{O-La 2 O 3 -Al 2} O 3 system, TeO ₂ -TiO ₂ -
_{Li 2 O-Na 2 O-} K 2 O system, TeO ₂ -TiO ₂ -
BaO-SiO _{system, TeO 2 -TiO 2 -La 2 O} 3 -
Al ₂ O ₃ system, TeO ₂ —TiO ₂ —ThO ₂ system, Te
_{O 2 -Ta 2 O 5 -Li 2} O-Na 2 O-K 2 O system, T
eO ₂ —Ta ₂ O ₅ —BaO—SrO system, TeO ₂ —N
_{b 2 O 5 -Li 2 O-} Na 2 O-K 2 O system, TeO ₂ -
_{Nb 2 O 5 -BaO-CaO-} SrO -based, TeO ₂ -N
b ₂ O ₅ -MgO-BeO system, TeO ₂ -Nb ₂ O ₅ -
La ₂ O ₃ -Al ₂ O ₃ system, TeO ₂ -Nb ₂ O ₅ -T
hO ₂ —TiO ₂ system, TeO ₂ —WO ₃ —K ₂ O—Li
₂ O-Na ₂ O-based, TeO ₂ -WO ₃ -BaO-CaO
-SrO system, TeO ₂ -WO ₃ -MgO-BeO system, T
eO ₂ -WO ₃ -La ₂ O ₃ -Al ₂ O ₃ system, TeO ₂
-WO ₃ -ThO ₂ -TiO ₂ system, TeO ₂ -WO ₃ -
Ta ₂ O ₅ —Nb ₂ O ₅ based glass or 2 of the above glasses
It was confirmed that the gain coefficient and the noise figure were improved when excited by 0.98 μm even when added to mixed glasses of more than one type.

[Embodiment 7] FIG. 3 shows an embodiment of the present invention. Reference numerals 11 and 11 'denote pumping semiconductor lasers (wavelength: 148).
0 nm), 12, 12 'are optical couplers for coupling signal light and pumping light, 13 and 15 are optical fibers for amplification, 14
Is an optical isolator, and is configured so that the signal light enters from the port A and then exits from the port B.

Er is 100 as the amplification fiber of 13.
ZrF ₄ type fluoride fiber (Ka
namori et al. Proceeding
of9th International Synpo
sium on Non-Oxide Glasse
s, P. 74, 1994), and TeO ₂ —Na doped with 1000 ppm of Er as 15 amplification fibers.
_{A 2} O-ZrO-Bi ₂ O ₃ -based oxidized telluride fiber was used.

The difference in the refractive index between the core and the cladding of each fiber is 2.5%, and the cutoff wavelength is 1.35 μ.
m and the fiber length were 10 m and 7 m, respectively. The output light intensity of the pumping semiconductor lasers 11 and 11 'was set to 150 mW, and the gain spectrum in the 1.5 μm band was measured.

FIG. 4 is a diagram showing the obtained gain spectrum. It can be seen that the gain has a value close to 30 dB and is flat in the 70 nm width from 1530 nm to 1600 nm. Therefore, the gain tilt can be suppressed to be small in this wavelength band. The wavelength width at which the gain becomes flat when an Er-doped fluoride fiber is used is 1530 n
Since it is 30 nm from m to 1560 nm, the wavelength width where the gain is flattened more than twice. In the case of Er-doped silica fiber, the flat wavelength width is at most 1
Since it is 0 nm, it means that it has expanded 7 times.

In the present embodiment, the Er-doped ZrF ₄ type fluoride fiber was used in the former stage and the Er-doped oxide telluride fiber was used in the latter stage, but the reverse is also possible and InF ₃
A system fluoride fiber may be used. Further, an Er-doped oxide multi-component glass fiber may be added to the amplification fiber. In short, it is important to use an Er-doped telluride oxide fiber as one of the amplification optical fibers.

The composition of the oxidized telluride fiber is not limited to that used in this embodiment.

It goes without saying that any one of forward pumping, backward pumping and bidirectional pumping may be used as the pumping method for the amplification optical fiber.

[Embodiment 8] FIG. 5 is a block diagram of this embodiment, in which the amplifying fibers 13 and 15 used in Embodiment 1 are connected in series to a wavelength tunable bandpass filter 17 (bandwidth 3 nm).
, And the transmittance is 99 at 16 1480 nm.
%, 100% reflectance from 1530 nm to 1630 nm
, And a mirror of 1530 nm to 163 at the other end
Laser oscillation was performed by providing a mirror 18 having a transmittance of 20% at 0 nm. As a result, it was possible to confirm laser oscillation in a wide range of 1530 nm to 1630 nm, which was 1.5 μm.
It has been found that it can be used as a high-bandwidth tunable laser that can be used in m.

[0051]

As described above, by using the optical amplification medium of the present invention, it is possible to construct an optical amplifier or a laser device of 1.6 μm to 1.7 μm which has been impossible with the optical fiber amplifier. As a result, high performance of the maintenance / monitoring system used in the 1.55 μm band optical communication system can be achieved, and stable operation of the optical communication system becomes possible.

Further, by utilizing the characteristic that the amplification wavelength range is wide, a short optical pulse such as femtosecond can be efficiently amplified, and it is also effective as an optical amplifier used in a wavelength division multiplexing optical transmission system.

Furthermore, in the Er-doped telluride oxide optical fiber amplifier, the gain coefficient by 0.98 μm pumping can be greatly improved, and high efficiency and low noise characteristics which cannot be realized by the conventional Er-doped oxide telluride optical fiber amplifier are achieved. can do.

By combining the characteristics realized this time with the high bandwidth inherent in the Er-doped telluride oxide optical fiber amplifier, it is possible to improve the performance of the WDM optical transmission system and the optical CATV system. It has the advantage that it can contribute significantly to the sophistication of the services used and the economy.

Further, if it is used as a wide band amplifier in a wavelength division multiplexing optical transmission system, the transmission capacity can be expected to be remarkably increased, which can contribute to the cost reduction of information communication. Also, optical CA
In a TV system, if it is used by utilizing the characteristic that the gain tilt is small, it is possible to distribute and relay a high-quality image by wavelength multiplexing, which has been difficult in the past, and it is also possible to reduce the cost of the optical CATV. There are merits. Further, if applied as a laser light source, it can contribute to cost reduction of various wavelength division multiplexing optical transmission systems and high performance of optical measurement.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an optical amplifier.

FIG. 2 is a configuration diagram showing an example of a laser device.

FIG. 3 is a configuration diagram of a laser device according to a seventh embodiment.

FIG. 4 is a diagram showing a gain spectrum obtained in Example 7.

FIG. 5 is a configuration diagram of a laser device according to an eighth embodiment.

FIG. 6 is an energy level diagram of Er ³⁺ .

FIG. 7 ⁴ I _13/2 → Er of Er in oxidized telluride glass
⁴ I _15/2 is a graph showing the emission spectrum.

[Explanation of symbols]

 1 signal light source 2 pumping light source 3 optical coupler 4 amplification optical fiber 5 optical isolator 6 optical fiber 7 narrow bandpass filter 11, 11 'pumping semiconductor laser 12, 12' optical coupler 13, 15 amplification optical fiber 14 optical isolator 16,18 Mirror 17 Wavelength variable bandpass filter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01S 3/10 Z 3/17 (72) Inventor Teruhisa Kanamori 1-1-1 Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corp. (72) Inventor Shoichi Sudo 1-1-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corp. (72) Inventor Makoto Shimizu 1-1-1-1 Uchiyukicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corp. (72) Inventor Tadashi Sakamoto 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corp.

Claims (7)

[Claims] 1. An optical amplification medium comprising an optical fiber at least having a core formed of glass doped with a rare earth element, wherein the glass is an oxide telluride-based glass doped with erbium. 2. An optical amplification medium comprising an optical fiber having at least a core made of a glass doped with a rare earth element, wherein the glass is an telluride oxide glass doped with erbium and ytterbium. Medium. 3. The telluride oxide glass is boron,
The optical amplification medium according to claim 1, which contains at least one of phosphorus and a hydroxyl group. 4. The optical amplification medium according to claim 1, and an input means for inputting pumping light and signal light for exciting the optical amplification medium to the optical amplification medium. Optical amplifier. 5. A laser device comprising: an optical resonator having at least a part of the optical amplification medium according to claim 1; and a pumping light source for exciting the optical amplification medium. . 6. An optical amplifier in which a plurality of optical amplifying media made of an optical fiber having at least a core doped with erbium are arranged in series, wherein at least one of the optical amplifying media has the light according to any one of claims 1 to 3. An optical amplifier characterized by using an amplification medium. 7. A laser device in which a plurality of optical amplification media made of an optical fiber having at least a core doped with erbium are arranged in series, wherein at least one of the optical amplification media has the light according to any one of claims 1 to 3. A laser device characterized by being used as an amplification medium.