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`Page 834 of 1542
`
`APPLIED MATERIALS EXHIBIT 1052 (Part 3 of 4)
`
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`04/25/2002, EAST Version: 1.03.0002
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`Page 835 of 1542
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`Page 836 of 1542
`
`

`

`PCT
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`WO 00/21898
`
`(SI) International Patent Classification 7 :
`C03C 13/04, H01S 3/06
`
`Al
`
`(11) International Publication Number:
`
`(43) International Publication Date:
`
`20 April 2000 (20.04.00)
`
`(21) International Application Number:
`
`PCT/KR99/00609
`
`(22) International Filing Date:
`
`11 October 1999 (11.10.99)
`
`(81) Designated States: AU, CA, CN, JP, RU, European patent
`(AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT,
`LU, MC, NL, PT, SE).
`
`Published
`With international search report.
`Before the expiration of the time limit for amending the
`claims and to be republished in the event of the receipt of
`amendments.
`
`(30) Priority Data:
`1998/42713
`
`13 October 1998 (13.10.98)
`
`KR
`
`(71) Applicant: SAMSUNG ELECTRONICS CO., LID. [KR/KR];
`416, Maetan-dong, Paldal-gu, Suwon-city, Kyunggi-do
`442-373 {KR).
`
`(72) Inventors: HEO, Jong; 8-401, Kyosoo Apt., Jigok-dong,
`Nam-gu, Pohang-city, Kyungsangbuk-do 790-390 (KR).
`LEE, Dong-chin; 7/1, 94-10, Onchun I-dong, Tongrae-gu,
`Pusan 607--061 {KR). PARK, Se-ho; 246-55, Junggok
`I-dong, Kwangjin-gu, Seoul 143-221 (KR).
`JUNG,
`Sun-tae; 602-1503, Taeyoung Apt., 1075, Hogae-dong,
`Tongan-gu, Anyang-city, Kyungki-do 431--080 (KR).
`KIM, Hyoun-soo; 801-1002 Jinheung Apt., Imae-dong,
`Bundang-gu, Sungnam-city, Kyungki-do 463--060 (KR).
`
`(74) Agent: LEE, Young-pi!; The Cheonghwa Building, 1571-18,
`Seocho-dong, Seocho-gu, Seoul 137--073 (KR).
`
`(S4) Title: OPTICAL FIBER FOR LIGHT AMPLIFIER
`
`(57) Abstract
`
`An optical fiber used for an optical amplifier, which is formed by doping glass with rare-earth ions.· Both praseodymiwn ions (Pr+-3)
`and erbium ions (Er3) are used as the rare-earth ions, and the glass is a fluoride glass or a sulfide glass. The optical fiber can be used
`at both wavelengths of 1.3 µm and 1.55 µm. The light amplification efficiency of an optical amplifier made of the optical fiber can be
`improved compared to an optical amplifier fonned of only Pr+3 or only Er+l.
`
`Page 837 of 1542
`
`

`

`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`AL
`AM
`AT
`AU
`AZ
`BA
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`cu
`CZ
`DE
`DK
`EE
`
`Albania
`Anncnia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`COie d'Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Ocnnany
`Denmark
`Estonia
`
`ES
`Fl
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`
`Lesotho
`LilhUlUlia
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`'The fonner Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romani.a
`Russian Federation
`Sudan
`Sweden
`Singapore
`
`SI
`SK
`SN
`sz
`TD
`TG
`TJ
`TM
`TR
`IT
`UA
`UG
`us
`uz
`VN
`YU
`zw
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
`t
`~
`
`Page 838 of 1542
`
`

`

`WO 00/21898
`
`PCT/KR99/00609
`
`1
`
`OPTICAL FIBER FOR LIGHT AMPLIFIER
`
`Technical Field
`
`The present invention relates to optical fibers for use in a light amplifier,
`
`5 and more particularly, to an optical fiber for use in a light amplifier which can
`be used at wavelengths of both 1.3 µm and 1.55 µm.
`
`Background Art
`
`The wavelength of light used in optical communications has been
`10 shifted from a wavelength of 1.3 µm to a wavelength of 1.55 µm. In general,
`praseodymium ions (Pr·~ which are used to dope an optical fiber, are used to
`amplify an optical signal having a wavelength of 1.3 µm while erbium ion (Er.3
`)
`which are used to dope an optical fiber, are used to amplify an optical signal
`having a wavelength of 1.55 µm.
`U.S. Patent No. 5,486,947 discloses an optical fiber for use in an optical
`
`15
`
`amplifier, which are capable of operating with optical sufficient optical gain at
`the 1.3 µm wavelength. The optical fiber is a fluoride glass optical fiber
`containing rare earth metal ions in a core glass, wherein the refractive index
`
`difference between the core and a cladding layer is above 1.4%, and the glass
`20 contains lead difluoride (PbF J in a proportion of 25 mol % or less based on the
`total composition for forming the glass.
`Now, both wavelengths of 1.3 µm and 1.55 µm are used in many optical
`communications related fields. Thus, different parts which are suitable for
`
`each wavelength, are req_uired to construct · an optical circuit, so that
`
`25 development cost increases in addition to switching cost for switching the
`
`wavelengths.
`
`Disclosure of the Invention
`
`30
`
`An object of the present invention is to provide an optical fiber for use
`in an optical amplifier, which can be used for both the 1.3 µm and 1.55 µm
`bands.
`
`Page 839 of 1542
`
`

`

`WO 00/21898
`
`PCT/KR99/00609
`
`2
`
`According to an aspect of the present invention, there is provided an
`
`optical fiber for an optical amplifier, which is formed by doping glass with rare(cid:173)
`) and erbium ions (Er+3
`earth ions, wherein both praseodymium ions (Pt3
`
`) are
`
`5
`
`used as the rare-earth ions, and the glass is a fluoride glass or a sulfide glass.
`Preferably, the content of Pt3 is 100-1000 ppm and the content of Er+3
`is 100-5000 ppm. If the Pr+3 and Er+3 content is outside the above range, light
`amplification efficiency is undesirably lowered. Also, the mixing ratio of Pr+3 to
`If the ratio of Pr•3 to E(3
`Er+3, by weight, may be between 1 :1 and 1 :3.
`exceeds the above ratio, fluorescence emission quantity at the wavelength of
`10 1.55 µm is decreased. Conversely, if the ratio of Pt3 to Ef3 is less than the
`above ratio, the amplification at the wavelength of 1.3 µm unfavorably
`
`decreased.
`
`Brief Description of the Drawings
`
`15
`
`, wherein
`
`FIG. 1 shows the fluorescence emission spectrum at wavelengths of 1.3
`µm and 1.55 µm according to the amount of Er•3 in optical fibers, when a laser
`beam having a wavelength of 980 nm is irradiated onto an optical fiber which
`is formed by doping glass made of Ge2gAs8Ga1S62 with Pr•3 and Er•3
`the fluorescence emission at the wavelength of 1.3 µm is caused by the
`level to the 3H5 level in Pr•3 doped
`20 electron transition of pr3• from the 10
`4
`fibers, and that at the wavelength of 1.55 µm is caused by the transition 411312
`.. 411512 in Er3· doped fibers ;
`FIG. 2 is a graph showing the fluorescence lifetime of Pr•3 at the 10 4
`level and of Et3 at the 411/2 level and 411/2 level according to the amount of
`25 Er•3 in optical fibers, when a ·laser beam having a wavelength of 980 nm is
`irradiated onto an optical fiber which is formed by doping a Ge2gAs8Ga1S62
`glass with Pr•3 and Er•3
`;
`FIG. 3 is a diagram illustrating energy transfer between Pr·3 and Er•3
`
`ions;
`
`30
`
`FIG. 4 shows the fluorescence emission spectrum at the wavelength of
`1.3 µm by the electron transition of Pr•3 from the 10 4 level to the 3H5 level
`when a laser beam having a wavelength of 1020 nm is irradiated onto an
`optical fiber which is formed by doping a Ge2gAs8Ga1S62 glass with Pr•3
`
`;
`
`Page 840 of 1542
`
`

`

`WO 00/21898
`
`PCT/KR99/00609
`
`3
`
`FIG. 5 shows the fluorescence emission spectrum at the wavelength of
`1.55 µm by the electron transition of Er+3 from the \
`312 level to the 411512 level
`when a laser beam having a wavelength of 980 nm is irradiated onto an optical
`fiber which is formed by doping a Ge2gAs8Ga1S62 glass with Er+3
`FIG. 6 shows the fluorescence emission spectrum at the wavelengths
`of 1.3 µm and 1.55 µm according to the amount of Pr+3 in optical fibers, when
`
`; and
`
`a laser beam having a wavelength of 980 nm is irradiated onto an optical fiber
`which is formed by doping a Ge2gAs8Ga1S62 glass with Pr+3 and Er+3, wherein
`the fluorescence emission at the wavelength of 1.3 µm is due to the electron
`transition of Pr+ from the 10 4 level to the 3H5 level, and that at the wavelength
`of 1.55 µm is due to the electron transition of Er3+ from the \
`312 level to the
`411512 level.
`
`5
`
`10
`
`Best mode for carrying out the Invention
`
`15
`
`The present invention provides an optical fiber for use in a light
`
`amplifier, which can be used at wavelengths of both 1.3 µm and 1.55 µm, by
`
`using a laser beam having a wavelength of 980 nm as .a light source for
`exciting an optical fiber formed of Pr+3 and Er+3
`
`• In the present invention, the
`
`term "fibers" refers ro shapes with a wide range of diameters, not merely thin
`
`20
`
`fibers. For example, a fiber may have diameter of 5 to 100mm. In the present
`invention, the fiber contains Pr+3 and Er+3
`, wherein the maximum absorption
`peak of Er+3 in a laser beam having wavelength 980 nm is at the 4111121evel.
`In this case, two ions are simultaneously excited, so that Pt3 emits
`fluorescence at 1.3 µm and Er+3 emits fluorescence at 1.55 µm. In particular,
`25 as shown in FIG. 3, the fluorescence lifetime of Pr+3 at the 10 4 level is
`elongated due to the energy transfer from Er+3
`, so that light amplification
`
`efficiency is improved compared to a conventional optical fiber containing only
`Pr+3.
`
`30
`
`Preferably, in the present invention, a fluoride or sulfide glass is used
`to minimize lattice vibration relaxation of Pr+3 from the 10 4 level to 3F 4 level.
`The fluoride glass may be a ZBLAN glass which is a fluoride containing
`
`zirconium (Zr), barium (Ba), lanthanum (La}, aluminum (Al) and sodium (Na},
`
`and the sulfide glass may be a germanium-arsenic-gallium-sulfur (Ge-As-Ga-
`
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`

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`
`PCT/KR99/00609
`
`4
`
`S) or Ge-As-S glass. Here, using the sulfide glass can further minimize the
`lattice vibration relaxation of Pr+3 from the 10 4 level to the 3F4 level compared
`to the case of using the fluoride glass. However, using the fluoride glass rather
`
`than a sulfide glass generally makes the manufacture of optical fiber easier.
`
`5
`
`In order to maximize the light amplification efficiency at both
`wavelengths of 1.3 µm and 1.55 µm, the mixing weight ratio of Pr·3 and Er•3 is
`
`adjusted to be between 1:1 and 1:3.
`
`Hereinafter, the present invention will be described using the following
`
`examples. However, these examples are merely illustrative and the present
`
`10
`
`invention is not limited thereto.
`
`Comparative Example 1
`
`Ge, As, Ga and Shaving a purity of 99.999% or more, were weighted
`
`in an atomic ratio of 29:8:1:62 in a glove box where the content of hydroxy
`
`15
`
`(OH) group and oxygen was maintained to be 10 ppm or less, and Pr metal
`powder was added in amount of 300 ppm to give the Pr•3
`•
`After filling a Si02 test tube with the above composition, the test tube
`was left under a vacuum condition of 0.1 mTorr for a predetermined period of
`
`time. Then, the test tube was made airtight by sealing it with an oxy-propane
`
`20
`
`flame.
`
`Following this, the test tube was put into a rocking furnace such that the
`
`composition comprised in the test tube was completely mixed, and the
`
`resultant was kept at 950°C for 12 hours. Then, the test tube was quenched
`
`in air, and heated in a furnace which was set at 400°C for 1 hour. After the
`
`25 heating process, the test tube was slowly cooled to room temperature and
`broken into pieces, resulting in an optical fiber formed of a Pr+3-doped sulfide
`glass of Ge~8Ga,S62 in which the amount of lattice vibration relaxation was
`slight. The optical fiber was cut into a disc shape (having a diameter of 10 mm
`
`and a thickness of 3 mm) and polished.
`Then, the fluorescence spectrum and fluorescence lifetime of the
`
`30
`
`resultant were measured using a laser beam having a wavelength of 1017
`nm as a source of light excitation. At this wavelength, Pt3 at the 10 4 level
`showed a maximum light absorption.
`
`Page 842 of 1542
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`PCT/KR99/00609
`
`5
`
`As a result, the fluorescence emission at a wavelength of 1.3 µm,
`which was caused by electron transition of Pr+3 from the 10 4 level to 3H5
`level, was observed (see FIG. 4), and the fluorescence lifetime was 305
`
`5
`
`10
`
`15
`
`µsec (see FIG. 2).
`
`Comparative Example 2
`
`An optical fiber was manufactured in the same manner as in
`Comparative Example 1 except that Er+3 was used instead of Pr+3
`• Er 2S3
`was used as the source of Et3
`• Then, the optical fiber was cut into a disc
`shape (having a diameter of 10 mm and a thickness of 3 mm) and polished.
`
`Then, the fluorescence spectrum and fluorescence lifetime of the resultant
`
`were measured using a laser beam having a wavelength of 980 nm as a
`source of light excitation. At this wavelength, Er+3 at the 411112 level showed
`a maximum light absorption.
`
`As a result, the fluorescence emission at a wavelength of 1.55 µm,
`which was caused by electron transition of Er+3 from the 411312 level to 411512
`level, was observed (see FIG. 5), and the fluorescence lifetime at the 411112
`411312 levels was 2100 µsec and 3400 µsec, respectively (see FIG. 2)
`and
`
`20
`
`Example 1
`
`An optical fiber was manufactured in the same manner as in
`Comparative Example 1 except that Er+3 was further added in the amount of
`300 ppm together with 300 ppm of Pr+3
`• Then, the optical fiber was cut into
`
`a disc shape (having a diameter of 1 O mm and a thickness of 3 mm) and
`
`25 polished. Then, the fluorescence spectrum and fluorescence lifetime of the
`
`resultant were measured using a laser beam having a wavelength of 980 nm
`as a source of light excitation. At this wavelength, Er+3 at the \ui. level
`showed a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`30 electron transition from 1G4 level to 3H5 level and that of Er+3
`, which was
`312 level to 411512 level were observed
`caused by electron transition from \
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`
`l
`
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`
`PCT/KR99/00609
`
`6
`
`FIG. 1 (a)). The intensify of fluorescence was increased at each wavelength
`compared to that of Comparative Examples 1-2. Also, the fluorescence
`lifetime of Pr+3 at the 10 4 level was 605 µsec, and the fluorescence lifetime
`of Er+3 at the
`levels was 824 µsec and 3120 µsec,
`\
`112 and \
`respectively (see FIG. 2).
`
`312
`
`5
`
`According to Example 1, as shown in FIG. 3, the simultaneous
`fluorescence emission at the wavelengths of 1.3 µm and 1.55 µm was due
`to the effective energy transfer indicated by "b". Thus, the optical fiber
`
`obtained in Example 1 can be used at wavelengths of both 1.3 µm and 1.55
`10 µm.
`
`15
`
`20
`
`Also, the fluorescence lifetime of Pr+3 at the 10 4 level was markedly
`elongated to 605 µsec compared to Comparative Example 1, and the light
`amplification efficiency at the wavelength of 1.3 µm was further improved by
`adding both Pr+3 and Er+3
`• However, the fluorescence lifetime of Er +3at the 411112
`level was 3120 µsec, which is lower than in. Comparative Example 2, thus
`lowering light amplification efficiency. This is due to the energy transfer
`
`indicated by "e".
`
`Example 2
`
`An optical fiber was manufactured in the same manner as in ·
`Comparative Example 1 except that 500 ppm of Er+3 was further added
`together with 300 ppm of Pt3
`• Then, the optical· fiber was cut into a disc
`shape (having a diameter of 10 mm and~ thickness of 3 mm) and polished.
`Then, the fluorescence spectrum and fluorescence lifetime of the resultant
`
`25 were measured using a laser beam having a wavelength of 980 nm as a
`source of light excitation. At this wavelength, Er+3 at the 411112 level showed
`a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`electron transition from 10 4 level to 3H5 level" and that of Et3
`, which was
`30 caused by electron transition from 411312 level to 411512 level were observed
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`
`FIG. 1 (b)). The intensify of fluorescence was increased at each wavelength
`
`Page 844 of 1542
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`

`W000/21898
`
`PCT/KR99/00609
`
`7
`
`compared to that of the Comparative Examples 1-2. Also, the fluorescence
`lifetime of P(3 at the 10 4 level was 760 µsec, and the fluorescent lifetime of
`Er+3 at the \
`112 and 411312 levels was 1740 µsec and 2910 µsec, respectively
`(see FIG. 2).
`
`5
`
`According to Example. 2, as shown in FIG. 3, the simultaneous
`
`fluorescence emission at the wavelengths of 1.3 µm and 1.55 µm was due
`
`to the effective energy transfer indicated by "b". Also, the fluorescence
`lifetime of Pr'~3 at the 10 4
`level was markedly elongated to 760 µsec
`compared to Comparative Example 1 and Example 1, and the fluorescence
`lifetime of Er+3 at the 411312 level was· decreased to 2910 µsec, compared to
`Comparative Example 2 and Example 1.
`
`From the above result, it can be understood that the energy transfer
`indicated by "b" and "e" occur more effectively as the content of Er+3
`increases. However, the fluorescence lifetime of Er+3 at the 411112 level was
`increased to 1740 µsec, compared to Example 1. As a result, it was
`concluded that as Et3
`• which is not involved in the energy transfer indicated
`by "b", increases, the energy transfer degree in the direction indicated by "b"
`
`10
`
`15
`
`decreases.
`
`20
`
`Example 3
`
`An optical fiber was manufactured in the same manner as in
`Comparative Example 1 except that 700 ppm of Er+3 was further added
`together with 300 ppm of Pt3
`• Then, the optical fiber was cut into a disc
`shape (having a diameter of 10 mm and a thickness of 3 mm) and polished.
`25 Then, the fluorescence spectrum and fluorescence lifetime of the resultant
`were measured using· a laser beam having a wavelength of 980 nm as a
`source of light excitation. At this wavelength, Er+3 at the 411112 level showed
`a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`30 electron transition from 10 4 level to 3H5 level and that of Er+3
`, which was
`312 level to 411512 level were observed
`caused by electron transition from \
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`
`Page 845 of 1542
`
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`

`WO 00/21898
`
`IPCT/KR99/00609
`
`8
`
`FIG. 1 (c}}. The intensify of fluorescence was increased at each wavelength
`compared to that of Examples 1-2. Also, the fluorescence lifetime of Pr+3 at
`the 1G4 level was 769 µsec, and the fluorescence lifetime of Et3 at the 4Iu12
`and \
`312 levels was 1760 µsec and 2920 µsec, respectively (see FIG. 2).
`According to Example 3, as the content of Er+3 increased, the
`fluorescence lifetime of Pr+3 at the 1G4 level was slightly increased. This
`was due to an increase in energy transfer indicated by "b" shown in FIG. 3.
`
`5
`
`lifetime at the \
`
`However, because Er+ was contributed for elongating the fluorescence
`112 and \ 3n. levels, the ratio of Er+3 associated with the
`10 energy transfer indicated by "b" and "e" was decreased, thus resulting in a
`slight increase in fluorescence lifetime of Pr+3 at the 1G4 level. That is, the
`light amplification efficiency at the wavelength of 1.55 µm showed a
`tendency to increases with an increase in the fluorescence lifetime of Er+3 at
`the 411312 level.
`
`15
`
`Example 4
`An optical fiber was manufactured in the same manner as in
`Comparative Example 1 except that 1000 ppm of Er+3 was further added
`together with 300 ppm of Pr+3
`• Then, the optical fiber was cut into a disc
`20 shape (having a diameter of 10 mm and a thickness of 3 mm} and polished.
`Then, the fluorescence spectrum and fluorescence lifetime of the resultant
`
`25
`
`were measured using a laser beam having a wavelength of 980 nm as a
`source of light excitation. At this wavelength, Er+3 at the \
`112 level showed
`a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`electron transition from 1G4 level to 3H5 level and that of Er+3
`, which was
`caused by electron transition from 411312 level to \
`512 level were observed
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`FIG. 1 (d)). The intensify of fluorescence was increased at each wavelength
`30 compared to that of Examples 1-3. Also, the fluorescence lifetime of Pr+3 at
`the 10 4 level was 881 .µsec, and the fluorescent lifetime of Er+3 at the 411111
`and 4113n. levels was 2030 µsec _and 3340 µsec, respectively (see FIG. 2).
`
`Page 846 of 1542
`
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`

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`
`PCT/KR99/00609
`
`9
`
`According to Example 4, as shown in FIG. 3, the simultaneous
`fluorescence emission at the wavelength of 1.3 µm by Pr+3 at the 10 4 level,
`and at the wavelength of 1.55 µm by Er+3 at the 4113a level, was due to
`effective energy transfer indicated by "b". Also, the fluorescence lifetime of
`5 Er+3 at the \
`112 and \
`312 levels showed the maximum levels. Thus, it can
`be understood that the mixing ratio of Pr+3 and e3 in this embodiment
`shows the maximum light amplification efficiency at both 1.3 µm and 1.55
`
`µm.
`
`10
`
`Example 5
`
`An optical fiber was manufactured by the same manner as in
`Comparative Example 1 except that 1500 ppm of Er+3 was further added
`together with 300 ppm of Pr+3
`• Then, the optical fiber was cut into a disc
`shape (having a diameter of 10 mm and a thickness of 3 mm) and polished.
`
`15 Then, the fluorescence spectrum and fluorescence lifetime of the resultant
`
`were measured . using a laser beam having a wavelength of 980 nm as a
`source of light excitation. At this wavelength, Er+3 at the 4111n level showed
`a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`20 electron transition from 10 4 level to 3H5 level and that of Er+3
`, which was
`caused by electron transition from \
`312 level to \
`512 level were observed
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`
`FIG. 1 (e)). The intensify of fluorescence was saturated, i.e., at the
`maximum level, at each wavelength. Also, the fluorescence lifetime of Pr+3
`25 at the 10 4 level was 794 µsec, and the fluorescence lifetime of Er+3 at the \
`112
`and \
`312 levels was 1870 µsec and 3240 µsec, respectively (see FIG. 2).
`According to Example 5, as shown in FIG. 3, the simultaneous
`fluorescence emission at the wavelength of 1.3 µm by Pt3 at the 10 4 level
`and at the wavelength of 1.55 µm by Et3 at the \
`3n level was due to
`30 effective energy transfer indicated by "b". The fluorescence lifetime of Er+3
`11.2 and \
`312 levels was slightly decreased compared to Example 4,
`because the energy transfer indicated by "b" and "e" were saturated.
`
`at the \
`
`Page 847 of 1542
`
`

`

`WO OO/l1898
`
`PCT/KR99/00609
`
`Example 6
`
`10
`
`Ge, Ga and Shaving a purity of 99.999% or more, were weighted in
`
`an atomic ratio of 25:5:70 in a glove box where the content of hydroxy (OH)
`group and oxygen was maintained to be 10 ppm or less, and 300 ppm of
`5 Pr+3 and 300 ppm of Er3 were added.
`After filling a Si02 test tube with the composition, the test tube was left
`under a vacuum condition of 0.1 mTorr for a predetermined period of time.
`
`Then, the test tube was made airtight by sealing it with an oxy-propane
`
`flame.
`
`10
`
`Following this, the test tube was put into a rocking furnace such that
`
`the composition comprised in the test tube was completely mixed, and the
`resultant was kept at 950°C for 12 hours. Then, the test tube was quenched
`in air, and heated in a furnace which was set at 260°C for 1 hour. After the
`heating process, the test tube was slowly cooled to room temperature and
`15 broken into pieces, resulting in an optical fiber formed of a Pt3 and Er3
`doped sulfide glass of Ge25Ga5S70 in which the amount of lattice vibration.
`relaxation was slight.
`The optical fiber was cut into a disc shape (having a diameter of 10
`mm and a thickness of 3 mm) and polished. Then, the fluorescence
`
`20
`
`spectrum and fluorescence lifetime of the resultant were measured using a
`laser beam having a wavelength of 980 nm as a source of light excitation.
`At this wavelength, Et3 at the 411112
`level showed a maximum light
`absorption.
`As a result, the fluorescence emission of Pt3
`, which was caused by
`25 electron transition from 10 4 level to 3H5 level and that of Er+3
`, which was
`caused by electron transition from 411312 level to 411512 level were observed
`simultaneously at the wavelengths of 1.3 µm arid 1.55 µm, respectively (see
`
`FIG. 6 (a)).
`
`According to Example 6, it can be unde'rstood that both a Ge-GA-S
`30 glass doped .with Pr+3 and Er3 and a Ge-As-Ga-S glass doped with Pr and
`Er+3 can be used as a material of an optical amplifier which can be used at
`
`both 1.3 µm and 1.55 µm.
`
`Page 848 of 1542
`
`

`

`W000/21898
`
`PCT/KR99/00609
`
`Example 7
`
`11
`
`An optical fiber was manufactured in the same manner as in Example
`6 except that the amount of Pt3 was increased to 500 ppm. Then, the
`optical fiber was cut into a disc shape (having a diameter of 1 O mm and a
`
`5
`
`thickness of 3 mm) and polished. Then, the fluorescence spectrum and
`
`fluorescence lifetime of the resultant were measured using a laser beam
`
`having a wavelength of 980 nm as a source of light excitation. At this
`wavelength, Er+3 at the 41.ia level showed a maximum light absorption.
`As a result, the fluorescence emission of Pr+3
`, which was caused by
`10 electron transition from 10 4 level to 3H5 level and that of Er+3
`, which was
`312 level to 411512 level were observed
`caused by electron transition from \
`simultaneously at the wavelengths of 1.3 µm and 1.55 µm, respectively (see
`FIG. 6 (b)). Also, as the amount of Pr+3 was increased, energy transfer in
`directions indicated by "b" and 11e11 in FIG. 3 increased. As a result, the
`fluorescence intensity of Pr+3 at the 10 4 level increased at the wavelength of
`1.3 µm, whereas that of Er+3 at the 411312 level decreased at the wavelength
`of 1.55 µm. However, the rate at which the fluorescence intensity increases
`at 1.3 µm is slower than the rate at which the fluorescence intensity
`
`15
`
`decreases at 1.55 µm, and thus it can be inferred that the energy transfer
`
`20
`
`indicated by "e" is more rapid than that i